[protoc_wrapper] Do not add --import-dir if it doesn't exist The original issue was `warning: directory does not exist` output in remote proto wrapper command. https://crrev.com/c/4812586 suppressed it by including --import-dir to remote inputs. But it turned out that it sometimes crushes Reproxy. This CL instead fixes `protoc_wrapper.py` to check the presence of `--import-dir`. Fixed: b/297428306, b/298129445 Change-Id: I79bb902af138d7517f8dbd82880639565c59d01d Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4829386 Reviewed-by: Dirk Pranke <dpranke@google.com> Reviewed-by: Fumitoshi Ukai <ukai@google.com> Commit-Queue: Junji Watanabe <jwata@google.com> Auto-Submit: Junji Watanabe <jwata@google.com> Cr-Commit-Position: refs/heads/main@{#1191120} NOKEYCHECK=True GitOrigin-RevId: 427382dd9083dc5c5d2b81975e0bdbb7c9300fce 1 file changed
