chore(db): remove 23 unused database methods (#22999)

Removes 22 database query methods with no callers outside generated code
and the dbauthz wrapper layer (~1,600 lines).

**Security keys (6)** — superseded by `cryptokeys` package:
`GetAppSecurityKey`, `UpsertAppSecurityKey`, `GetOAuthSigningKey`,
`UpsertOAuthSigningKey`, `GetCoordinatorResumeTokenSigningKey`,
`UpsertCoordinatorResumeTokenSigningKey`

**Superseded queries (4):**
- `GetProvisionerJobsByIDs` → `GetProvisionerJobsByIDsWithQueuePosition`
- `GetDeploymentDAUs` / `GetTemplateDAUs` →
`GetTemplateInsightsByInterval`
- `GetWorkspaceBuildParametersByBuildIDs` + its `GetAuthorized...`
variant → unused

**OAuth2 (2):**
`GetOAuth2ProviderAppByRegistrationToken`,
`UpdateOAuth2ProviderAppSecretByID`

**Chat (4)** — pre-wired with no callers:
`GetChatModelConfigByProviderAndModel`, `DeleteChatMessagesByChatID`,
`ListChatsByRootID`, `ListChildChatsByParentID`

**Other (6):**
`DeleteGitSSHKey`, `UpdateUserLinkedID`, `GetFileIDByTemplateVersionID`,
`GetTemplateVersionHasAITask`, `InsertUserGroupsByName`,
`RemoveUserFromAllGroups`

coderd/database/queries/chatmodelconfigs.sql

@@ -16,21 +16,6 @@ WHERE
     is_default = TRUE
     AND deleted = FALSE;
 
--- name: GetChatModelConfigByProviderAndModel :one
-SELECT
-    *
-FROM
-    chat_model_configs
-WHERE
-    provider = @provider::text
-    AND model = @model::text
-    AND deleted = FALSE
-ORDER BY
-    updated_at DESC,
-    created_at DESC,
-    id DESC
-LIMIT 1;
-
 -- name: GetChatModelConfigs :many
 SELECT
     *