Set worker numbers using variables in azure pipeline library (#6927)

Approach
What is the motivation for this PR?
Previously, we hard code the min and max numbers of instance in a plan. In this pr, we support passing the instance numbers of a testplan.

How did you do it?
Use a variable to set the instance number.

How did you verify/test it?
Any platform specific information?
Supported testbed topology if it's a new test case?

.azure-pipelines/run-test-scheduler-template.yml

@@ -11,11 +11,11 @@ parameters:
   default: 36000
 
 - name: MIN_WORKER
-  type: number
+  type: string
   default: 1
 
 - name: MAX_WORKER
-  type: number
+  type: string
   default: 2
 
 - name: NUM_ASIC

azure-pipelines.yml

@@ -73,8 +73,8 @@ stages:
     - template: .azure-pipelines/run-test-scheduler-template.yml
       parameters:
         TOPOLOGY: t0
-        MIN_WORKER: 2
-        MAX_WORKER: 3
+        MIN_WORKER: $(T0_INSTANCE_NUM)
+        MAX_WORKER: $(T0_INSTANCE_NUM)
 
   - job: t0_2vlans_testbedv2
     displayName: "kvmtest-t0-2vlans by TestbedV2"
@@ -86,7 +86,8 @@ stages:
       parameters:
         TOPOLOGY: t0
         TEST_SET: t0-2vlans
-        MAX_WORKER: 1
+        MIN_WORKER: $(T0_2VLANS_INSTANCE_NUM)
+        MAX_WORKER: $(T0_2VLANS_INSTANCE_NUM)
         DEPLOY_MG_EXTRA_PARAMS: "-e vlan_config=two_vlan_a"
 
   - job:
@@ -146,8 +147,8 @@ stages:
     - template: .azure-pipelines/run-test-scheduler-template.yml
       parameters:
         TOPOLOGY: t1-lag
-        MIN_WORKER: 2
-        MAX_WORKER: 3
+        MIN_WORKER: $(T1_LAG_INSTANCE_NUM)
+        MAX_WORKER: $(T1_LAG_INSTANCE_NUM)
 
   - job:
     displayName: "kvmtest-t1-lag"
@@ -193,8 +194,8 @@ stages:
       - template: .azure-pipelines/run-test-scheduler-template.yml
         parameters:
           TOPOLOGY: t0-64-32
-          MIN_WORKER: 1
-          MAX_WORKER: 2
+          MIN_WORKER: $(T0_SONIC_INSTANCE_NUM)
+          MAX_WORKER: $(T0_SONIC_INSTANCE_NUM)
           TEST_SET: t0-sonic
           COMMON_EXTRA_PARAMS: "--neighbor_type=sonic --enable_macsec --macsec_profile=128_SCI,256_XPN_SCI"
           VM_TYPE: vsonic
@@ -225,8 +226,8 @@ stages:
       - template: .azure-pipelines/run-test-scheduler-template.yml
         parameters:
           TOPOLOGY: dualtor
-          MIN_WORKER: 1
-          MAX_WORKER: 1
+          MIN_WORKER: $(T0_DUALTOR_INSTANCE_NUM)
+          MAX_WORKER: $(T0_DUALTOR_INSTANCE_NUM)
           COMMON_EXTRA_PARAMS: "--disable_loganalyzer "
 
   - job:
@@ -255,8 +256,8 @@ stages:
         parameters:
           TOPOLOGY: t1-8-lag
           TEST_SET: multi-asic-t1-lag
-          MIN_WORKER: 1
-          MAX_WORKER: 1
+          MIN_WORKER: $(MULTI_ASIC_INSTANCE_NUM)
+          MAX_WORKER: $(MULTI_ASIC_INSTANCE_NUM)
           NUM_ASIC: 4
 
   - job: wan_testbedv2
@@ -268,6 +269,6 @@ stages:
       - template: .azure-pipelines/run-test-scheduler-template.yml
         parameters:
           TOPOLOGY: wan-pub
-          MIN_WORKER: 1
-          MAX_WORKER: 1
+          MIN_WORKER: $(WAN_INSTANCE_NUM)
+          MAX_WORKER: $(WAN_INSTANCE_NUM)
           COMMON_EXTRA_PARAMS: "--skip_sanity "