ci: do not install firebase-tools without cache (#28615)

Currently we install `firebase-tools` manually in the
integration tests run script. This is problematic
because it means that we cannot cache `firebase-tools`
properly and Yarn might time out downloading this
dependency. We can safely move this to the top level
`package.json` since Bazel now has a `.bazelignore` and
since we have a cache that works for PRs (with fallback
caching).

Note that the `.bazelignore` is relevant here because
`firebase-tools` has been mainly moved to the bash
script because it broke some Bazel calls.

See 4f0cae067656fa4563417542297c67030d911a36.

PR Close #28615

integration/run_tests.sh

@@ -15,10 +15,6 @@ readonly basedir=$(pwd)/..
 # and the maximum amount of shards available for the integration tests on the CI.
 # For example: "./run_tests.sh {SHARD_INDEX} {MAX_SHARDS}".
 if $CI; then
-  # We don't install this by default because it contains some broken Bazel setup
-  # and also it's a very big dependency that we never use except when publishing
-  # payload sizes on CI.
-  yarn add --silent -D firebase-tools@5.1.1
   source ${basedir}/scripts/ci/payload-size.sh
 
   SHARD_INDEX=${1:?"No shard index has been specified."}

package.json

@@ -114,6 +114,7 @@
     "core-js": "^2.4.1",
     "cors": "2.8.4",
     "entities": "1.1.1",
+    "firebase-tools": "5.1.1",
     "firefox-profile": "1.0.3",
     "glob": "7.1.2",
     "gulp": "3.9.1",