Remove third_party/jsr-305 from gn check directories.

The directory //third_party/jsr-305 has recently been removed.

Bug: 1070424
Change-Id: I2a3da25ee64ffcf28a6f59274af02656d6e71d76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2170346
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#763498}

.gn

@@ -419,7 +419,6 @@ check_targets = [
   "//third_party/javax_inject/*",
   "//third_party/jinja2/*",
   "//third_party/jsoncpp/*",
-  "//third_party/jsr-305/*",
   "//third_party/jstemplate/*",
   "//third_party/junit/*",
   "//third_party/khronos/*",