[web] use a global shared mock for the metrics module (#32799)

GitOrigin-RevId: 72874ba6c06c2a602b01cc029bc9c71ce3ce8892

services/web/test/unit/src/SplitTests/SplitTestHandler.test.mjs

@@ -68,9 +68,6 @@ describe('SplitTestHandler', function () {
     ctx.SessionManager = {
       isUserLoggedIn: sinon.stub().returns(false),
     }
-    ctx.Metrics = {
-      inc: sinon.stub(),
-    }
 
     Features = {
       hasFeature: vi.fn().mockReturnValue(true),
@@ -132,8 +129,6 @@ describe('SplitTestHandler', function () {
       default: ctx.Settings,
     }))
 
-    vi.doMock('@overleaf/metrics', () => ({ default: ctx.Metrics }))
-
     ctx.SplitTestHandler = (await import(MODULE_PATH)).default
 
     ctx.req = new MockRequest(vi)