Don't warn on linelength from cpplint

Summary:
Both clangformat and cpplint enforce line length. The former autofixes
but the latter doesn't. This means that when you `arc diff` the commit is autofixed
but the error from cpplint propogates down. Instead just rely on clangformat to
both enforce and autofix linelength.

Test Plan:
Edited some cpp files to make extra long lines. Ran arc lint. Verified
that clangformat autofixed the lines and cpplint didn't complain.

Reviewers: nserrino, zasgar, philkuz

Reviewed By: zasgar, philkuz

Signed-off-by: Vihang Mehta <vihang@pixielabs.ai>

Differential Revision: https://phab.corp.pixielabs.ai/D11163

GitOrigin-RevId: 33e7252

.arclint

@@ -66,7 +66,7 @@
         "--filter=-build/c++11",
         "--filter=-build/c++14",
         "--filter=-legal/copyright",
-        "--linelength=100"
+        "--filter=-whitespace/line_length"
       ]
     },
     "eslint-ui": {