[CI] Use 32 cores for clang-tidy CI job (#36838)

This task was parallelized into 16 sub-tasks, but 32 cores are available. Let's see if this speeds up CI, the clang-tidy job usually takes about 30m to 40m.

Closes #36838

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36838 from drfloob:tidy-32 81edd68348
PiperOrigin-RevId: 641014003

tools/internal_ci/linux/grpc_clang_tidy.cfg

@@ -26,5 +26,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests linux clang-tidy --inner_jobs 16 -j 1 --internal_ci --bq_result_table aggregate_results"
+  value: "-f basictests linux clang-tidy --inner_jobs 32 -j 1 --internal_ci --bq_result_table aggregate_results"
 }

tools/internal_ci/linux/pull_request/grpc_clang_tidy.cfg

@@ -26,5 +26,5 @@ action {
 
 env_vars {
   key: "RUN_TESTS_FLAGS"
-  value: "-f basictests linux clang-tidy --inner_jobs 16 -j 1 --internal_ci"
+  value: "-f basictests linux clang-tidy --inner_jobs 32 -j 1 --internal_ci"
 }