[ci] Set timeout for individual tests and report slowest tests (#76300)

There are builds like
https://buildkite.com/llvm-project/github-pull-requests/builds/24894

It looks like a deadlock in a test, but we can't see which one.
`--timeout=` will make lit kill and report such tests.

`--time-tests` produces nice report about slowest test, so we can tune
them over time.

The same build as above with new flags
https://buildkite.com/llvm-project/github-pull-requests/builds/24961

.ci/monolithic-linux.sh

@@ -45,7 +45,7 @@ cmake -S ${MONOREPO_ROOT}/llvm -B ${BUILD_DIR} \
       -D LLVM_ENABLE_ASSERTIONS=ON \
       -D LLVM_BUILD_EXAMPLES=ON \
       -D COMPILER_RT_BUILD_LIBFUZZER=OFF \
-      -D LLVM_LIT_ARGS="-v --xunit-xml-output ${BUILD_DIR}/test-results.xml" \
+      -D LLVM_LIT_ARGS="-v --xunit-xml-output ${BUILD_DIR}/test-results.xml --timeout=1200 --time-tests" \
       -D LLVM_ENABLE_LLD=ON \
       -D CMAKE_CXX_FLAGS=-gmlt \
       -D BOLT_CLANG_EXE=/usr/bin/clang \

.ci/monolithic-windows.sh

@@ -45,7 +45,7 @@ cmake -S ${MONOREPO_ROOT}/llvm -B ${BUILD_DIR} \
       -D LLVM_ENABLE_ASSERTIONS=ON \
       -D LLVM_BUILD_EXAMPLES=ON \
       -D COMPILER_RT_BUILD_LIBFUZZER=OFF \
-      -D LLVM_LIT_ARGS="-v --xunit-xml-output ${BUILD_DIR}/test-results.xml" \
+      -D LLVM_LIT_ARGS="-v --xunit-xml-output ${BUILD_DIR}/test-results.xml --timeout=1200 --time-tests" \
       -D COMPILER_RT_BUILD_ORC=OFF \
       -D CMAKE_C_COMPILER_LAUNCHER=sccache \
       -D CMAKE_CXX_COMPILER_LAUNCHER=sccache \