infra: fuzz-introspector: ensure COVERAGE_URL exists (#7502)
infra: fuzz-introspector: ensure COVERAGE_URL exists (#7502)

* infra: fuzz-introspector: ensure COVERAGE_URL exists

This is to make sure fuzz-introspector can run in local builds.

Ref:
https://github.com/ossf/fuzz-introspector/issues/48#issuecomment-1087513497
Ref:
https://github.com/ossf/fuzz-introspector/issues/67#issuecomment-1087518856

* refactor fuzz-introspector command generation

This is to shorten the long line that runs fuzz-introspector and also in
anticipation that down the line we will have more oss-fuzz specific
commands in fuzz-introspector
skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,skia-dev/oss-fuzz,google/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,google/oss-fuzz,google/oss-fuzz,skia-dev/oss-fuzz,robertswiecki/oss-fuzz