add --norun_validations to bazel build action

Validation actions were being run before the build environment was set
up and causing build errors. Turn off validation actions in this phase
because they will be run later in the Ninja invocation.

Bug: 195029134
Test: build/bazel/ci/mixed_libc.sh
Test: verify that Ninja build file contains commands to generate tidy
  files that are generated by these validation actions
Test: delete a tidy file in mixed builds mode, and verify that it is
  rebuilt
Change-Id: I371572d5662913c5637e39c8894eeb6ee53d00ac