fix(platform/gerrit): URI encode branch in gerrit's getFile() (#30753)

lib/modules/platform/gerrit/client.spec.ts

@@ -415,11 +415,11 @@ describe('modules/platform/gerrit/client', () => {
       httpMock
         .scope(gerritEndpointUrl)
         .get(
-          '/a/projects/test%2Frepo/branches/main/files/renovate.json/content',
+          '/a/projects/test%2Frepo/branches/base%2Fbranch/files/renovate.json/content',
         )
         .reply(200, gerritFileResponse('{}'));
       await expect(
-        client.getFile('test/repo', 'main', 'renovate.json'),
+        client.getFile('test/repo', 'base/branch', 'renovate.json'),
       ).resolves.toBe('{}');
     });
   });

lib/modules/platform/gerrit/client.ts

@@ -195,7 +195,7 @@ class GerritClient {
     const base64Content = await this.gerritHttp.get(
       `a/projects/${encodeURIComponent(
         repo,
-      )}/branches/${branch}/files/${encodeURIComponent(fileName)}/content`,
+      )}/branches/${encodeURIComponent(branch)}/files/${encodeURIComponent(fileName)}/content`,
     );
     return Buffer.from(base64Content.body, 'base64').toString();
   }