perf: Various performance regression fixes (#38078)

Fixes five N+1 / O(n) query patterns found across common user paths.
Each uses a bulk query that already existed elsewhere in the codebase.

| Location | Problem | Introduced in |
| -------------------------------- |
-------------------------------------------------------------------------------------------------------------------------------
| ------------- |
| `IssueList.LoadIsRead` | `.In("issue_id")` missing its arg — xorm
generates `WHERE 0=1`, so `IsRead` is **never** set; every issue always
appears unread | #29515 |
| `ParseCommitsWithStatus` | `GetLatestCommitStatus` called once per
commit (O(n) queries on commit list / PR commits tab) | #33605 |
| `getReleaseInfos` (release list) | `GetLatestCommitStatus` called once
per release for CI badges | #29149 |
| User milestone dashboard | O(n×m) nested loop matching milestones to
repos | #26300 |
| `findCodeComments` (PR diff) | `LoadResolveDoer` + `LoadReactions`
called per inline comment — up to ~150 queries on a PR with 50 comments
| #20821 |

---------

Co-authored-by: Lauris B <lauris@nix.lv>

models/issues/issue_list.go

@@ -591,9 +591,12 @@ func (issues IssueList) GetApprovalCounts(ctx context.Context) (map[int64][]*Rev
 
 func (issues IssueList) LoadIsRead(ctx context.Context, userID int64) error {
 	issueIDs := issues.getIssueIDs()
+	if len(issueIDs) == 0 {
+		return nil
+	}
 	issueUsers := make([]*IssueUser, 0, len(issueIDs))
 	if err := db.GetEngine(ctx).Where("uid =?", userID).
-		In("issue_id").
+		In("issue_id", issueIDs).
 		Find(&issueUsers); err != nil {
 		return err
 	}