[ci]: use native armhf and arm64 pool (#965)

Signed-off-by: Guohan Lu <[email protected]>

Author: lguohan

.azure-pipelines/build-template.yml

@@ -10,6 +10,8 @@ parameters:
   type: string
   values:
   - sonicbld
+  - sonicbld-arm64
+  - sonicbld-armhf
   - default
   default: default
 

azure-pipelines.yml

@@ -37,7 +37,7 @@ stages:
     parameters:
       arch: armhf
       timeout: 240
-      pool: sonicbld
+      pool: sonicbld-armhf
       sonic_slave: sonic-slave-buster-armhf
       swss_common_artifact_name: sonic-swss-common.armhf
       artifact_name: sonic-sairedis.armhf
@@ -47,7 +47,7 @@ stages:
     parameters:
       arch: arm64
       timeout: 240
-      pool: sonicbld
+      pool: sonicbld-arm64
       sonic_slave: sonic-slave-buster-arm64
       swss_common_artifact_name: sonic-swss-common.arm64
       artifact_name: sonic-sairedis.arm64