refactor: fix legacy problems in cmd/serv.go (#38505)

1. use var names "reqOwnerName, reqRepoName", because these values are
from request and should not be really used for path construction
2. simplify enable-pprof logic, don't "log.Fatal"
3. don't make runServe command to guess the repo storage path, instead,
let server return RepoStoragePath
4. don't process lfs verbs when the repo is a wiki
5. construct the request URI path correctly for the lfs transfer backend
(moved to the caller)
6. don't call "owner, err := user_model.GetUserByName", the "owner
rename redirection" has been done before
7. fix incorrect "repo.OwnerName = ownerName", the real owner might have
been "redirected"
8. fix incorrect "inactive owner" check, it should be checked even if
the repo is redirected


Use general error functions to handle responses, error handling code is
hugely simplified.

modules/private/serv.go

@@ -43,6 +43,8 @@ type ServCommandResults struct {
 	OwnerName   string
 	RepoName    string
 	RepoID      int64
+
+	RepoStoragePath string
 }
 
 // ServCommand preps for a serv call