Remove --extra_toolchains flag from aquery runner

When specifying --extra_toolchains=//prebuilts/clang/host/linux-x86:all, there is no control over the sort order of toolchains, which can result in a more generic toolchain being used rather than the most specific (and correct) toolchain.

Apparently, this flag is causing Bazel to drop some flags from CppCompile actions. This causes mixed-build's outputs different from Soong build. The mixed-build also generates different from Bazel build because we don't use the flag when using `b` to build the targets.

Test: Inspect differences in CppCompile actions from Soong's Bazel aquery handler and b aquery
Bug: 273995121
Change-Id: Id9e32c0cd12ab8577cd5b223ca9e19c982f3ae1f