Updated the 2021-06-01-preview attestation defintions and fixed (#24124)

versions:

- Updated `2021-06-01-preview/attestation.json` to match the internal swagger defintions.
- Fixed versions in the examples

Squashed commit of the following:

commit 51d3137
Author: Olga Kroshkina <olkroshk@microsoft.com>
Date:   Tue Oct 4 16:01:55 2022 -0700

    [Public/Global - Microsoft Azure Attestation Service] Commit # 3 - Fixed issues in the public API, added TPM Attestation auth switch

commit ab07e7b
Author: Olga Kroshkina <olkroshk@microsoft.com>
Date:   Tue Oct 4 15:19:42 2022 -0700

    [Public/Global - Microsoft Azure Attestation Service] Commit # 2 - Updated the API version with the 2021-06-01 value

commit 96bd39e
Author: Olga Kroshkina <olkroshk@microsoft.com>
Date:   Tue Oct 4 15:05:43 2022 -0700

    [Public/Global - Microsoft Azure Attestation Service] Commit # 1 - Copy of preview/2021-06-01-preview

Author: olkroshk

specification/attestation/resource-manager/Microsoft.Attestation/preview/2021-06-01-preview/attestation.json

@@ -110,7 +110,7 @@
           "AttestationProviders"
         ],
         "operationId": "AttestationProviders_Create",
-        "description": "Creates a new Attestation Provider.",
+        "description": "Creates or updates an Attestation Provider.",
         "x-ms-examples": {
           "AttestationProviders_Create": {
             "$ref": "./examples/Create_AttestationProvider.json"

specification/attestation/resource-manager/Microsoft.Attestation/preview/2021-06-01-preview/examples/AttestationProviderDeletePrivateEndpointConnection.json

@@ -4,7 +4,7 @@
     "resourceGroupName": "res6977",
     "providerName": "sto2527",
     "privateEndpointConnectionName": "{privateEndpointConnectionName}",
-    "api-version": "2019-06-01",
+    "api-version": "2021-06-01-preview",
     "monitor": "true"
   },
   "responses": {

specification/attestation/resource-manager/Microsoft.Attestation/preview/2021-06-01-preview/examples/AttestationProviderListPrivateEndpointConnections.json

@@ -3,7 +3,7 @@
     "subscriptionId": "{subscription-id}",
     "resourceGroupName": "res6977",
     "providerName": "sto2527",
-    "api-version": "2019-06-01",
+    "api-version": "2021-06-01-preview",
     "monitor": "true"
   },
   "responses": {

specification/attestation/resource-manager/Microsoft.Attestation/preview/2021-06-01-preview/examples/AttestationProviderPutPrivateEndpointConnection.json

@@ -4,7 +4,7 @@
     "resourceGroupName": "res7687",
     "providerName": "sto9699",
     "privateEndpointConnectionName": "{privateEndpointConnectionName}",
-    "api-version": "2019-06-01",
+    "api-version": "2021-06-01-preview",
     "monitor": "true",
     "properties": {
       "properties": {

specification/attestation/resource-manager/Microsoft.Attestation/preview/2021-06-01-preview/examples/Get_AttestationProvidersListByResourceGroup.json

@@ -2,7 +2,7 @@
   "parameters": {
     "resourceGroupName": "testrg1",
     "subscriptionId": "6c96b33e-f5b8-40a6-9011-5cb1c58b0915",
-    "api-version": "2018-09-01-preview"
+    "api-version": "2021-06-01-preview"
   },
   "responses": {
     "200": {