Fix output=locations display source file location

[zhengwei143]

This PR is a patch to fix this commit after being brought up here.

The goal of this PR is to align the output of --output=location with its current definition in the documentation. With the flag --output=location, source files are supposed to output "the location of line 1 of the actual file" but only displayed its location in the BUILD file prior to the commit.

Expected behavior by definition:

bazel query bazeltest:main.py --output=location
/home/tanzhengwei/bazeltest/main.py:1:1: source file //bazeltest:main.py

The previous commit wrongly modified the output to the following (with the --incompatible_display_source_file_location flag):

bazel query bazeltest:main.py --output=location --incompatible_display_source_file_location
/home/tanzhengwei/bazeltest/BUILD:1:10: source file /home/tanzhengwei/bazeltest/main.py:1:1

This PR fixes it to output to the correct implementation (with the --incompatible_display_source_file_location flag):

bazel query bazeltest:main.py --output=location --incompatible_display_source_file_location
/home/tanzhengwei/bazeltest/main.py:1:1: source file //bazeltest:main.py

[benjaminp]

lgtm—thank you

[meisterT]

Benjamin, thank you for calling this out!