maintner/maintnerd/maintapi: test x/tools with Go 1.19+1.18 longer

We've been able to extend LUCI test coverage for the needs of gopls,
which makes Kokoro CI testing that previously provided said testing
obsolete. What I failed to realize until trying to clean up after it
is that it's still load bearing during the gradual transition to LUCI.
That is, someone may test a CL using the old trybots, get a passing
result, and submit.

That'll be quite annoying as it'd cause a breakage only when using the
new LUCI trybots, so I'd rather not leave this possibility in for long.

I can bring back the Kokoro CI and delete it later, or make x/tools
require LUCI trybots sooner, but perhaps a simpler path for now is to
manually extend coordinator trybots to include 1.19+1.18 in x/tools.
The same approach worked for x/website needs in CL 393858 and CL 456715.

Change-Id: If4f72049200ceb6e8d2286849d11cfdba98e4de2
Reviewed-on: https://go-review.googlesource.com/c/build/+/528155
Reviewed-by: Dmitri Shuralyov <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Heschi Kreinick <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

maintner/maintnerd/maintapi/api.go

@@ -209,6 +209,22 @@ func tryWorkItem(
 				w.GoBranch = append(w.GoBranch, r.BranchName)
 				w.GoVersion = append(w.GoVersion, &apipb.MajorMinor{Major: r.Major, Minor: r.Minor})
 			}
+
+			// Test x/tools with Go 1.19+1.18 in addition to the supportedReleases above,
+			// to mirror behavior implemented in LUCI. This is needed only until x/tools
+			// stops accepting legacy trybot results or x/tools stops needing to support
+			// these Go versions, whichever happens first. Relevant only if that happens
+			// before the migration to LUCI is complete.
+			// See https://go.googlesource.com/tools/+/HEAD/gopls/#supported-go-versions.
+			if w.Project == "tools" {
+				w.GoCommit = append(w.GoCommit, "619b8fd7d2c94af12933f409e962b99aa9263555") // go1.19.13 tag.
+				w.GoBranch = append(w.GoBranch, "release-branch.go1.19")
+				w.GoVersion = append(w.GoVersion, &apipb.MajorMinor{Major: 1, Minor: 19})
+
+				w.GoCommit = append(w.GoCommit, "581603cb7d02019bbf4ff508014038f3120a3dcb") // go1.18.10 tag.
+				w.GoBranch = append(w.GoBranch, "release-branch.go1.18")
+				w.GoVersion = append(w.GoVersion, &apipb.MajorMinor{Major: 1, Minor: 18})
+			}
 		} else {
 			// A branch that is neither internal-branch.goX.Y-suffix nor "master":
 			// maybe some custom branch like "dev.go2go".