net/http/cgi: Remove hard-coded ServeHTTP timeout
net/http/cgi: Remove hard-coded ServeHTTP timeout

Close #43624

Change-Id: Ifaea3d8ec2aeabbd923abf5edd7497172dbf855a
GitHub-Last-Rev: ea3ef953a1dbbb07c4554e4062571af716e9505b
GitHub-Pull-Request: golang/go#43803
Reviewed-on: https://go-review.googlesource.com/c/go/+/284778
Reviewed-by: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Run-TryBot: Bryan C. Mills <1c8aad60184261ccede67f5c63a0d2a3bf3c9ff4@google.com>
Trust: Robert Findley <9179eee875d1ee628c37fb47d7e749e855ffd21f@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/go,nawawi/go,cloudflare/go,CAFxX/go,cloudflare/go,golang/go,nawawi/go,nawawi/go,golang/go,nawawi/go,nawawi/go,nawawi/go,CAFxX/go,CAFxX/go,golang/go,cloudflare/go,cloudflare/go,cloudflare/go,CAFxX/go,golang/go,golang/go,CAFxX/go,cloudflare/go,CAFxX/go,cloudflare/go,CAFxX/go,CAFxX/go,golang/go,golang/go,cloudflare/go,nawawi/go,nawawi/go