config test: use acbgrep

Use acbgrep, in order to provide better error messages when `grep`
fails.

Signed-off-by: Alex Couture-Beil <[email protected]>

tests/config/Earthfile

@@ -10,7 +10,7 @@ test:
  COPY expected-*.yml .
 
  # Ensure earthly doesn't create overridden config files when they don't exist
- RUN earthly --config config.yml config global.disable_analytics true 2>&1 | grep 'failed to read from config.yml: open config.yml: no such file or directory'
+ RUN earthly --config config.yml config global.disable_analytics true 2>&1 | acbgrep 'failed to read from config.yml: open config.yml: no such file or directory'
 
  RUN touch config.yml
 
@@ -98,15 +98,15 @@ test:
  # check permission error is correctly returned
  COPY hello.earth Earthfile
  RUN ! earthly --config=/tmp/config.yml --verbose +hello > output.txt 2>&1
- RUN cat output.txt | grep 'Error: read config: failed to read from /tmp/config.yml: open /tmp/config.yml: permission denied'
+ RUN cat output.txt | acbgrep 'Error: read config: failed to read from /tmp/config.yml: open /tmp/config.yml: permission denied'
 
  # check permission error is correctly returned even when earthly attempts to read from the default location
  # to make this test work, a symbolic link is required (chown root:root /home/testuser/.earthly/config.yml doesnt work)
  RUN rm /home/testuser/.earthly/config.yml
  RUN ln -s /tmp/config.yml /home/testuser/.earthly/config.yml
 
  RUN ! earthly --verbose +hello > output.txt 2>&1
- RUN cat output.txt | grep 'Error: read config: failed to read from /home/testuser/.earthly/config.yml: open /home/testuser/.earthly/config.yml: permission denied'
+ RUN cat output.txt | acbgrep 'Error: read config: failed to read from /home/testuser/.earthly/config.yml: open /home/testuser/.earthly/config.yml: permission denied'
 
  # make it obvious that this test passed, due to the previous grep displaying "Error: ..." when it passes
  RUN echo "config test passed"