Drop 2.11.0-rc issue template

The 2.11.0 release is out now.

It reverts PR #8367.

NO_DOC=no code changes
NO_CHANGELOG=see NO_DOC
NO_TEST=see NO_DOC

.github/ISSUE_TEMPLATE/2-11-0-rc.md

----
-name: 2.11.0-rc
-about: Users's feedback regarding 2.11.0 release candidates
-title: "[2.11.0-rc] <...>"
-labels: 2.11.0-rc
----
-
-Tarantool version: 2.11.0-rc<...>.
-
-**Problem description**
-
-<..OS/architecture/other metainformation..>
-
-<..a description of the problem..>
-
-**Steps to reproduce**
-
-test.lua file:
-
-```lua
-#!/usr/bin/env tarantool
-
-<...>
-```
-
-**Actual behavior**
-
-<..a clear and concise description of what you see..>
-
-**Expected behavior**
-
-<..a clear and concise description of what you expected to happen..>