Switch from inline HTML to Markdown for code in topic

Fixes compatibility problems with markdownlint-cli 0.29.0

doc/development/database/efficient_in_operator_queries.md

@@ -66,9 +66,9 @@ The execution of the query can be largely broken down into three steps:
 1. The database sorts the `issues` rows in memory by `created_at` and returns `LIMIT 20` rows to
    the end-user. For large groups, this final step requires both large memory and CPU resources.
 
-<details>
-<summary>Expand this sentence to see the execution plan for this DB query.</summary>
-<pre><code>
+Execution plan for this DB query:
+
+```sql
  Limit  (cost=90170.07..90170.12 rows=20 width=1329) (actual time=967.597..967.607 rows=20 loops=1)
    Buffers: shared hit=239127 read=3060
    I/O Timings: read=336.879
@@ -106,8 +106,7 @@ The execution of the query can be largely broken down into three steps:
  Planning Time: 7.750 ms
  Execution Time: 967.973 ms
 (36 rows)
-</code></pre>
-</details>
+```
 
 The performance of the query depends on the number of rows in the database.
 On average, we can say the following:
@@ -240,9 +239,9 @@ to make the query execute efficiently:
 "idx_issues_on_project_id_and_created_at_and_id" btree (project_id, created_at, id)
 ```
 
-<details>
-<summary>Expand this sentence to see the SQL query.</summary>
-<pre><code>
+The SQL query:
+
+```sql
 SELECT "issues".*
 FROM
   (WITH RECURSIVE "array_cte" AS MATERIALIZED
@@ -353,8 +352,7 @@ SELECT (records).*
    FROM "recursive_keyset_cte" AS "issues"
    WHERE (COUNT <> 0)) issues -- filtering out the initializer row
 LIMIT 20
-</code></pre>
-</details>
+```
 
 ### Using the `IN` query optimization
 
@@ -466,9 +464,9 @@ Gitlab::Pagination::Keyset::InOperatorOptimization::QueryBuilder.new(
 ).execute.limit(20)
 ```
 
-<details>
-<summary>Expand this sentence to see the SQL query.</summary>
-<pre><code>
+The SQL query:
+
+```sql
 SELECT "issues".*
 FROM
   (WITH RECURSIVE "array_cte" AS MATERIALIZED
@@ -586,9 +584,7 @@ FROM
    FROM "recursive_keyset_cte" AS "issues"
    WHERE (COUNT <> 0)) issues
 LIMIT 20
-</code>
-</pre>
-</details>
+```
 
 NOTE:
 To make the query efficient, the following columns need to be covered with an index: `project_id`, `issue_type`, `created_at`, and `id`.