disable eslint rule etc/no-deprecated for massive file save speedup (#57782)

With this rule enabled, saving a file in VS Code often takes 2-5 seconds or longer. With it disabled, saving a file is usually instant.

This rule is identified as the biggest culprit in slow eslint analysis by running `TIMING=1 pnpm exec eslint --fix client/web/dev/server/development.server.ts`.

.eslintrc.js

@@ -242,6 +242,7 @@ See https://handbook.sourcegraph.com/community/faq#is-all-of-sourcegraph-open-so
       },
     ],
     'import/order': 'off',
+    'etc/no-deprecated': 'off',
   },
   overrides: [
     {

client/shared/src/codeintel/legacy-extensions/lsif/definition-hover.test.ts

@@ -1,4 +1,3 @@
-/* eslint-disable etc/no-deprecated */
 import * as assert from 'assert'
 
 import * as sinon from 'sinon'

client/shared/src/codeintel/legacy-extensions/lsif/providers.test.ts

@@ -1,4 +1,3 @@
-/* eslint-disable etc/no-deprecated */
 import * as assert from 'assert'
 
 import * as sinon from 'sinon'

client/shared/src/codeintel/legacy-extensions/lsif/references.test.ts

@@ -1,4 +1,3 @@
-/* eslint-disable etc/no-deprecated */
 import * as assert from 'assert'
 
 import * as sinon from 'sinon'

client/shared/src/codeintel/legacy-extensions/search/providers.test.ts

@@ -1,4 +1,3 @@
-/* eslint-disable etc/no-deprecated */
 import * as assert from 'assert'
 
 import * as sinon from 'sinon'