send vg alerts only when thin pool alerts are also triggered

[sp98]

Trigger VolumeGroupUsage alerts only if actual size is occupied via the thin pool.
VolumeGroupUsageAtThresholdNearFull will be sent when used VG size and
thin pool size exceeds 75%.

VolumeGroupUsageAtThresholdCritical will be sent when VG size and thin
pool size exceeds 85%.

Testing

Current behavior: size-percent is 90

sh-4.4# vgs
  VG  #PV #LV #SN Attr   VSize  VFree
  vg3   1   1   0 wz--n- <1.46t 149.04g
sh-4.4# lvs
  LV          VG  Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  thin-pool-3 vg3 twi-a-tz-- <1.31t             0.00   9.94

• VG critical alert trigger even though thin pool is not using any real space.
  

---

Behavior after this PR:

• size percent is 90

sh-4.4# vgs
  VG  #PV #LV #SN Attr   VSize  VFree  
  vg4   1   1   0 wz--n- <1.46t 149.04g
sh-4.4# lvs
  LV          VG  Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  thin-pool-4 vg4 twi-a-tz-- <1.31t             0.00   9.94                            
sh-4.4# 

• No VG critical alert triggered.

• Thin pool used data bytes cross 85%

sh-4.4# vgs
  VG  #PV #LV #SN Attr   VSize  VFree  
  vg4   1   2   0 wz--n- <1.46t 149.04g
sh-4.4# lvs
  LV                                   VG  Attr       LSize  Pool        Origin Data%  Meta%  Move Log Cpy%Sync Convert
  fa87dbd5-b437-40b8-8fd1-827a464df10a vg4 Vwi-aotz--  1.27t thin-pool-4        92.93                                  
  thin-pool-4                          vg4 twi-aotz-- <1.31t                    90.37  56.11   

Both thin pool and vg alerts are triggered.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[sp98]

Tests are not looking good. Volume Group alerts are not firing. Looking into that.

[iamniting]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: iamniting, nbalacha, sp98

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