add secondary poll factor to flex counter infra

[apoorv-arista]

Build Order Requirements

┌──────────────────────────────┐
│  sonic-swss-common (#1110)   │  ◄── Foundation (no dependencies)
└──────────────────────────────┘
         │                  
         │                  
         ├──────────────────────────┐
         │                          │
         │                          │
         v                          │
┌──────────────────────────────┐    │
│  sonic-sairedis (#1699)      │    │
│  depends on:                 │    │
│    - sonic-swss-common       │    │
└──────────────────────────────┘    │
         │                          │
         │                          │
         └──────────┬───────────────┘
                    │
                    v
         ┌──────────────────────────────┐
         │  sonic-swss (#4002)          │
         │  depends on:                 │
         │    - sonic-sairedis          │
         │    - sonic-swss-common       │
         └──────────────────────────────┘

Build Order (bottom-up):
sonic-swss-common (#1110) - build first
sonic-sairedis (#1699) - build second
sonic-swss (#4002) - build last
PR Merge Order: The PRs should be merged in the same order: #1110 → #1699 → #4002

[mssonicbld]

/azp run

[azure-pipelines]

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