Set +x to bazel_determinism_test.sh and srcs_test.sh

The import script failed to add them and none of our presubmit caught it.

PiperOrigin-RevId: 166193514
diff --git a/src/test/shell/bazel/bazel_determinism_test.sh b/src/test/shell/bazel/bazel_determinism_test.sh
old mode 100644
new mode 100755
diff --git a/src/test/shell/bazel/srcs_test.sh b/src/test/shell/bazel/srcs_test.sh
old mode 100644
new mode 100755