Fix creation of Organization repos by Users with max created personal repos (#11183)

* Fix creation of Org repos

Fix go-gitea#9269

* Change variable name to appease linter

* Update PR with suggestions

Add a note for user.CanCreateRepo() about failure assumptions
Change repo.create help message

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

templates/repo/create.tmpl

@@ -31,6 +31,7 @@
 								{{end}}
 							</div>
 						</div>
+						<span class="help">Some organizations may not show up in the dropdown due to a maximum repository count limit</span>
 					</div>
 
 					<div class="inline required field {{if .Err_RepoName}}error{{end}}">