Use today's cache only (#14120)

### Description
Add date value of today into the cache key.

### Motivation and Context
Microsoft-host agent has only 10GB for build.
To limit cache size, pipeline only use cache generated today.

tools/ci_build/github/azure-pipelines/linux-ci-pipeline.yml

@@ -14,6 +14,7 @@ jobs:
   variables:
     skipComponentGovernanceDetection: true
     CCACHE_DIR: $(Pipeline.Workspace)/ccache
+    TODAY: $[format('{0:dd}{0:MM}{0:yyyy}', pipeline.startTime)]
   pool: Linux-CPU-2019
   steps:
   - task: mspremier.PostBuildCleanup.PostBuildCleanup-task.PostBuildCleanup@3
@@ -42,12 +43,12 @@ jobs:
 
   - task: Cache@2
     inputs:
-      key: '"ccache" | "$(Build.SourceBranch)" | "$(Build.SourceVersion)"'
+      key: '"$(TODAY)" | "$(Build.SourceBranch)" | "$(Build.SourceVersion)"'
       path: $(CCACHE_DIR)
       cacheHitVar: CACHE_RESTORED
       restoreKeys: |
-        "ccache" | "$(Build.SourceBranch)"
-        "ccache"
+        "$(TODAY)" | "$(Build.SourceBranch)"
+        "$(TODAY)" |
     displayName: Cach Task
 
   - script: |