Allow clang and gcc builds for `src/e2e_test/vizier/planner:planner_t…

…est` (#2077)

Summary: Allow clang and gcc builds for
`src/e2e_test/vizier/planner:planner_test`

As far as I can tell, there isn't a bazel config that matches the tags
of the `src/e2e_test/vizier/planner:planner_test` target. This change
removes the tag preventing clang builds since they appear to run without
problems. In addition to this, a `vispb` proto change was missing from
the earlier differential flamegraph work. This prevented the
`planner_test` from running properly (see comment for more details).

Relevant Issues: N/A

Type of change: /kind bugfix

Test Plan: Verified gcc and clang builds work
- [x] `bazel test --config clang
src/e2e_test/vizier/planner:planner_test` is successful
- [x] `bazel test -c opt --config gcc
src/e2e_test/vizier/planner:planner_test` is successful

---------

Signed-off-by: Dom Del Nano <[email protected]>
GitOrigin-RevId: 685ed42f5baa6eaba4b7105fd3264a4b37b16ac4