Upgrade to bazel 7.5.0 (envoyproxy#38268)

Bazel 7.5.0 lands the coverage changes needed to drop the hack in
`.github/workflows/mobile-coverage.yml`.

Risk Level: Low
Testing: CI

Signed-off-by: Alejandro R. Sedeño <[email protected]>

Author: asedeno

.bazelversion

@@ -1 +1 @@
-7.4.0
+7.5.0

.github/workflows/mobile-coverage.yml

@@ -58,13 +58,6 @@ jobs:
           run: |
             cd mobile
             tar -czf coverage.tar.gz generated/coverage
-      # TODO(phlax): This is a highly undesirable workaround - remove once
-      #   https://github.com/bazelbuild/bazel/issues/23247 is resolved/available
-      steps-pre: |
-        - name: Inject bazel version
-          shell: bash
-          run: |
-            echo "7.1.2" > .bazelversion
       target: mobile-coverage
       timeout-minutes: 120
       upload-name: coverage.tar.gz