Add th6 getMaxAclEntries value in AclScaleTestUtils.h

[cel-gl]

Pre-submission checklist
[heshiw@AZUHPS26 fboss]$ git commit -m "Add th6 getMaxAclEntries value in AclScaleTestUtils.h"
clang-format.............................................................Passed
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check yaml...........................................(no files to check)Skipped
check json...........................................(no files to check)Skipped
check for merge conflicts................................................Passed

Summary

AgentNSFScaleTest.Test test fail on icetea and other th6 platforms, root cause getMaxAclEntries doesn't support th6 , after modify as below show, and add acl group related configs in agent, the case passed

Test Plan

config change : "enable_acl_table_group": "true",

add
"aclTableGroup": {
"name": "acl-table-group-ingress",
"aclTables": [
{
"name": "AclTable1",
"priority": 0,
"aclEntries": [

  ],
  "actionTypes": [
    
  ],
  "qualifiers": [
    
  ],
  "udfGroups": [
    
  ]
}

],
"stage": 0
},
"aclTableGroups": [
{
"name": "acl-table-group-ingress",
"aclTables": [
{
"name": "AclTable1",
"priority": 0,
"aclEntries": [

    ],
    "actionTypes": [
      
    ],
    "qualifiers": [
      
    ],
    "udfGroups": [
      
    ]
  }
],
"stage": 0

}
],

tested on icetea passed

[cel-gl]

@huruinan