goLanguageService.ts: gopls update check logic is broken at head

[hyangah]

Parsing GOPROXY format in goProxyRequest is broken
and fails to handle values likehttps://proxy.golang.org,direct

cc @stamblerre

[stamblerre]

Oh wow I should've really read the documentation for split. I'll mail a fix ASAP.

[gopherbot]

Change https://golang.org/cl/239739 mentions this issue: goLanguageServer: fix proxy update logic

[gopherbot]

Change https://golang.org/cl/239741 mentions this issue: goLanguageServer: fix proxy update logic