Prevent GLES2 bool uniforms from having a precision type set.
When setting the default precision type for uniforms (before compiling
the shader) prevent boolean uniforms from having one set. Booleans can't
have a precision type and on some Android devices this caused a
compilation failure.
Fixes #30317
(cherry picked from commit 10f1e0f63a53a9261101cbef28e1be2b7706a7a7)