Revert "seems to be the simplier path" - Fix dockerfilelint -c option usage

[past-due]

@admiralAwkbar:

Unfortunately commit 1da8c13 does not work for similar reasons to those listed in @LukeMondy's comment: https://github.com/github/super-linter/issues/305#issuecomment-651571788 (I have tested with and without this commit.)

(The GetLinterRules function sets LANGUAGE_LINTER_RULES to a path including the filename again.)

I suppose we could also modify how GetLinterRules works, but reverting this commit seems like the easier solution - given all other linters seem to expect a path including the filename - and fixes the use of the dockerfilelintrc file.

Note: dockerfilelint silently proceeds with default settings if the path provided to the -c option doesn't match what it expects, so it's critical to test with (a) a dockerfile that triggers default warnings and (b) a custom dockerfilelintrc file that disables them

Fixes #355

Proposed Changes

• This reverts commit 1da8c13, which seems the simplest change to fix the dockerfilelintrc functionality (without substantial other changes to functions like GetLinterRules for this singular exception).

Readiness Checklist

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[admiralAwkbar]

@past-due amazing work! sorry for not properly testing it.

thanks again!

[LukeMondy]

@past-due thanks for doing all this 👍