Use a capital B to represent bytes in download progress

Change the download progress to use a capital B to represent bytes instead of a lowercase b (which normally represents bits).

Old behavior:
```
    Fetching @go_sdk; fetching 69s
    Fetching ...; 19,298,881b 69s
```

New behavior:
```
    Fetching @go_sdk; fetching 69s
    Fetching ...; 19,298,881B 69s
```

Closes #10743.

PiperOrigin-RevId: 294248160
diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/DownloadProgressEvent.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/DownloadProgressEvent.java
index 5d74ddc..637c794 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/DownloadProgressEvent.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/DownloadProgressEvent.java
@@ -75,7 +75,7 @@
     if (bytesRead > 0) {
       NumberFormat formatter = NumberFormat.getIntegerInstance(Locale.ENGLISH);
       formatter.setGroupingUsed(true);
-      return formatter.format(bytesRead) + "b";
+      return formatter.format(bytesRead) + "B";
     } else {
       return "";
     }