maintner/maintnerd/maintapi: use project~numericId ID type in goFindTryWork
maintner/maintnerd/maintapi: use project~numericId ID type in goFindTryWork

In rare cases, the project~branch~Change-Id change ID type will not
uniquely identify a Gerrit CL. Switch to the suggested¹ identifier
type project~numericId which can handle those cases.

¹ https://gerrit-review.googlesource.com/Documentation/rest-api-changes.html#change-id

Fixes golang/go#43312.

Change-Id: I17b6afecd45fc456cd1a2aec3c727f9b90b5a3ef
Reviewed-on: https://go-review.googlesource.com/c/build/+/279672
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Trust: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>

golang/build,golang/build,golang/build,golang/build