Fix the GC robot testcase fail issue (#23214)

Signed-off-by: stonezdj <stone.zhang@broadcom.com>

Author: stonezdj

tests/robot-cases/Group1-Nightly/Common_GC.robot

@@ -53,7 +53,7 @@ Test Case - Garbage Collection
     GC Now  workers=5
     ${latest_job_id}=  Get Text  ${latest_job_id_xpath}
     Retry GC Should Be Successful  ${latest_job_id}  7 blobs and 1 manifests eligible for deletion
-    Retry GC Should Be Successful  ${latest_job_id}  The GC job actual frees up 34 MB space
+    Retry GC Should Be Successful  ${latest_job_id}  The GC job actual frees up 34.14 MB space
     Close Browser
 
 Test Case - GC Untagged Images