Add issue template for query performance

Relates to https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/7743#note_212379866

Add issue template for query performance
Relates to https://gitlab.com/gitlab-com/gl-infra/infrastructure/issues/7743#note_212379866
20b470a2 · Andreas Brandl · f4e40c53 · 20b470a2
--- a/.gitlab/issue_templates/Database Query Performance Review.md
+++ b/.gitlab/issue_templates/Database Query Performance Review.md
+### Query
+
+<!--
+Ideally format the query, e.g. with http://sqlformat.darold.net
+
+Please obtain a query plan through ChatOps or otherwise from production.
+Please use representative query parameter values.
+Please post a link to https://explain.depesz.com below if the plan is
+large.
+-->
+
+```sql
+SELECT 1
+```
+
+Plan: <!-- link to https://explain.depesz.com/ -->
+
+### Statistics
+
+|                                      |                              |
+| ---                                  |  ------                      |
+| Observation range                    | <!-- time or date range -->  |
+| Frequency (calls per minute)         |                              |
+| Average execution time (ms)          |                              |
+| Total database time during range (s) |                              |
+
+
+### Analysis
+
+<!--
+Suggestion, proposed change, analysis of query plan and similar
+-->
+
+### Code
+
+<!--
+Where is this query used? Link to code base. This can be added later upon investigation, too.
+-->
+
+/label ~Database ~"Database Engineering" ~performance ~"needs investigation"
+cc @gl-database