Closes #20631: remove @Ignore on StorageStats tests.

The errors that caused this to be @Ignored were addressed by a recent PR
landing on master (i.e. the one that renewed the probes this test is
testing).

app/src/test/java/org/mozilla/fenix/perf/StorageStatsMetricsTest.kt

@@ -16,7 +16,6 @@ import mozilla.components.support.test.robolectric.testContext
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Before
-import org.junit.Ignore
 import org.junit.Rule
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -42,7 +41,6 @@ class StorageStatsMetricsTest {
     }
 
     @Test
-    @Ignore("These metrics have expired.")
     fun `WHEN reporting THEN the values from the storageStats are accumulated`() {
         every { storageStats.appBytes } returns 100
         every { storageStats.cacheBytes } returns 200
@@ -56,7 +54,6 @@ class StorageStatsMetricsTest {
     }
 
     @Test
-    @Ignore("These metrics have expired.")
     fun `WHEN reporting THEN the query duration is measured`() {
         StorageStatsMetrics.reportSync(mockContext)
         assertTrue(Metrics.queryStatsDuration.testHasValue())