Set the local CPU reservation for tests based on their "cpu:<n>" tag.

This lets users specify that their test needs a minimum of <n> CPU cores
to run and not be flaky. Example for a reservation of 4 CPUs:

sh_test(
  name = "test",
  size = "large",
  srcs = ["test.sh"],
  tags = ["cpu:4"],
)

This could also be used by remote execution strategies to tune their
resource adjustment.

RELNOTES: You can increase the CPU reservation for tests by adding a "cpu:<n>" (e.g. "cpu:4" for four cores) tag to their rule in a BUILD file. This can be used if tests would otherwise overwhelm your system if there's too much parallelism.
PiperOrigin-RevId: 154856091

site/versions/master/docs/test-encyclopedia.html

diff --git a/site/versions/master/docs/test-encyclopedia.html b/site/versions/master/docs/test-encyclopedia.html
index b0eca8b..6a9b0e8 100644
--- a/site/versions/master/docs/test-encyclopedia.html
+++ b/site/versions/master/docs/test-encyclopedia.html
@@ -332,7 +332,9 @@
 <h4>Other resources</h4>
 
 <p>Tests are granted at least one CPU core. Others may be available but this
-is not guaranteed. Other performance aspects of this core are not specified.</p>
+is not guaranteed. Other performance aspects of this core are not specified.
+You can increase the reservation to a higher number of CPU cores by adding the
+tag "cpu:n" (where n is a positive number) to a test rule.</p>
 
 <p>Tests may create subprocesses, but not process groups or sessions.</p>