Remove CoverageOutputGenerator from the bazel binary.

Use a remote archive for retrieving the CoverageOutputGenerator deploy jar.

The bazel binary size goes down 4M:

```
$ git fetch origin remove-coverageoutputgenerator
$ bazel build -c opt //src:bazel && ls -lh bazel-bin/src/bazel | awk {'print $5'}
70M

$ git checkout master
$ bazel build -c opt //src:bazel && ls -lh bazel-bin/src/bazel | awk {'print $5'}
74M
```

Closes #7981.

PiperOrigin-RevId: 242695838
diff --git a/WORKSPACE b/WORKSPACE
index 6f9c474..3b50f81 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -112,6 +112,7 @@
         "java_tools_javac10_linux-x86_64-v2.1.zip",
         "java_tools_javac10_windows-x86_64-v2.1.zip",
         "java_tools_javac10_darwin-v2.1.zip",
+        "coverage_output_generator-v1.0.zip",
         "2d9566b21fbe405acf5f7bf77eda30df72a4744c.tar.gz",
         "8ccf4f1c351928b55d5dddf3672e3667f6978d60.tar.gz",
         "0.16.2.zip",
@@ -124,6 +125,7 @@
         "java_tools_javac10_linux-x86_64-v2.1.zip": "9163c9963f31e10101d538163c435db9534baf9db63d380508311b775fbe3c37",
         "java_tools_javac10_windows-x86_64-v2.1.zip": "a7a99e34213eb80384b81dda0217582a38f876f420c7b648900f254bf9ea3bd7",
         "java_tools_javac10_darwin-v2.1.zip": "5f6a7abf7ec0c491dc2d0b15add6a2abb594e31809f4cabc2cfde41efa995f92",
+        "coverage_output_generator-v1.0.zip": "cc470e529fafb6165b5be3929ff2d99b38429b386ac100878687416603a67889",
         "2d9566b21fbe405acf5f7bf77eda30df72a4744c.tar.gz": "4a1318fed4831697b83ce879b3ab70ae09592b167e5bda8edaff45132d1c3b3f",
         "8ccf4f1c351928b55d5dddf3672e3667f6978d60.tar.gz": "d868ce50d592ef4aad7dec4dd32ae68d2151261913450fac8390b3fd474bb898",
         "0.16.2.zip": "9b72bb0aea72d7cbcfc82a01b1e25bf3d85f791e790ddec16c65e2d906382ee0",
@@ -147,6 +149,9 @@
         "java_tools_javac10_darwin-v2.1.zip": [
             "https://mirror.bazel.build/bazel_java_tools/releases/java_tools_javac10_darwin-v2.1.zip",
         ],
+        "coverage_output_generator-v1.0.zip": [
+            "https://mirror.bazel.build/bazel_coverage_output_generator/releases/coverage_output_generator-v1.0.zip",
+        ],
         "2d9566b21fbe405acf5f7bf77eda30df72a4744c.tar.gz": [
             "https://mirror.bazel.build/github.com/bazelbuild/skydoc/archive/2d9566b21fbe405acf5f7bf77eda30df72a4744c.tar.gz",
             "https://github.com/bazelbuild/skydoc/archive/2d9566b21fbe405acf5f7bf77eda30df72a4744c.tar.gz",
@@ -339,6 +344,7 @@
         "java_tools_javac10_linux-x86_64-v2.1.zip",
         "java_tools_javac10_windows-x86_64-v2.1.zip",
         "java_tools_javac10_darwin-v2.1.zip",
+        "coverage_output_generator-v1.0.zip",
         "zulu11.2.3-jdk11.0.1-linux_x64.tar.gz",
         "zulu11.2.3-jdk11.0.1-macosx_x64.tar.gz",
         "zulu11.2.3-jdk11.0.1-win_x64.zip",
@@ -360,6 +366,7 @@
         "java_tools_javac10_linux-x86_64-v2.1.zip": "9163c9963f31e10101d538163c435db9534baf9db63d380508311b775fbe3c37",
         "java_tools_javac10_windows-x86_64-v2.1.zip": "a7a99e34213eb80384b81dda0217582a38f876f420c7b648900f254bf9ea3bd7",
         "java_tools_javac10_darwin-v2.1.zip": "5f6a7abf7ec0c491dc2d0b15add6a2abb594e31809f4cabc2cfde41efa995f92",
+        "coverage_output_generator-v1.0.zip": "cc470e529fafb6165b5be3929ff2d99b38429b386ac100878687416603a67889",
         "zulu11.2.3-jdk11.0.1-linux_x64.tar.gz": "232b1c3511f0d26e92582b7c3cc363be7ac633e371854ca2f2e9f2b50eb72a75",
         "zulu11.2.3-jdk11.0.1-macosx_x64.tar.gz": "1edf366ee821e5db8e348152fcb337b28dfd6bf0f97943c270dcc6747cedb6cb",
         "zulu11.2.3-jdk11.0.1-win_x64.zip": "8e1e2b8347de6746f3fd1538840dd643201533ab113abc4ed93678e342d28aa3",
@@ -380,6 +387,7 @@
         "java_tools_javac10_linux-x86_64-v2.1.zip": ["https://mirror.bazel.build/bazel_java_tools/releases/java_tools_javac10_linux-x86_64-v2.1.zip"],
         "java_tools_javac10_windows-x86_64-v2.1.zip": ["https://mirror.bazel.build/bazel_java_tools/releases/java_tools_javac10_windows-x86_64-v2.1.zip"],
         "java_tools_javac10_darwin-v2.1.zip": ["https://mirror.bazel.build/bazel_java_tools/releases/java_tools_javac10_darwin-v2.1.zip"],
+        "coverage_output_generator-v1.0.zip": ["https://mirror.bazel.build/bazel_coverage_output_generator/releases/coverage_output_generator-v1.0.zip"],
         "zulu11.2.3-jdk11.0.1-linux_x64.tar.gz": ["https://mirror.bazel.build/openjdk/azul-zulu11.2.3-jdk11.0.1/zulu11.2.3-jdk11.0.1-linux_x64.tar.gz"],
         "zulu11.2.3-jdk11.0.1-macosx_x64.tar.gz": ["https://mirror.bazel.build/openjdk/azul-zulu11.2.3-jdk11.0.1/zulu11.2.3-jdk11.0.1-macosx_x64.tar.gz"],
         "zulu11.2.3-jdk11.0.1-win_x64.zip": ["https://mirror.bazel.build/openjdk/azul-zulu11.2.3-jdk11.0.1/zulu11.2.3-jdk11.0.1-win_x64.zip"],