chore: Update discovery artifacts (#1325)

## Deleted keys were detected in the following stable discovery artifacts:
apigeev1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/9106808da3e03faa4c27913358e0c07edd82ff5a)

## Discovery Artifact Change Summary:
apigeev1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/9106808da3e03faa4c27913358e0c07edd82ff5a)
dataflowv1b3[ [More details]](https://github.com/googleapis/google-api-python-client/commit/9dd646184e70a83831f3347fc01a3eb0090ca0e8)
dialogflowv2[ [More details]](https://github.com/googleapis/google-api-python-client/commit/a7f2e96e6b283771e986d9ec7f1f057ff67e2a29)
dialogflowv2beta1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/a7f2e96e6b283771e986d9ec7f1f057ff67e2a29)
dialogflowv3[ [More details]](https://github.com/googleapis/google-api-python-client/commit/a7f2e96e6b283771e986d9ec7f1f057ff67e2a29)
documentaiv1beta3[ [More details]](https://github.com/googleapis/google-api-python-client/commit/ee1318d36230ff4b7393ce1f15d6a9ee71d23cea)
healthcarev1[ [More details]](https://github.com/googleapis/google-api-python-client/commit/1204c1d486e08630773812ff1cc35843d98eb1d8)

feat(apigee): update the api
feat(dataflow): update the api
feat(dialogflow): update the api
feat(documentai): update the api
feat(healthcare): update the api

diff --git a/docs/dyn/dataflow_v1b3.projects.templates.html b/docs/dyn/dataflow_v1b3.projects.templates.html
index d319230..7f0db54 100644
--- a/docs/dyn/dataflow_v1b3.projects.templates.html
+++ b/docs/dyn/dataflow_v1b3.projects.templates.html
@@ -463,6 +463,9 @@
     "name": "A String", # Required. The name of the template.
     "parameters": [ # The parameters for the template.
       { # Metadata for a specific parameter.
+        "customMetadata": { # Optional. Additional metadata for describing this parameter.
+          "a_key": "A String",
+        },
         "helpText": "A String", # Required. The help text to display for the parameter.
         "isOptional": True or False, # Optional. Whether the parameter is optional. Defaults to false.
         "label": "A String", # Required. The label to display for the parameter.
@@ -477,6 +480,9 @@
   "runtimeMetadata": { # RuntimeMetadata describing a runtime environment. # Describes the runtime metadata with SDKInfo and available parameters.
     "parameters": [ # The parameters for the template.
       { # Metadata for a specific parameter.
+        "customMetadata": { # Optional. Additional metadata for describing this parameter.
+          "a_key": "A String",
+        },
         "helpText": "A String", # Required. The help text to display for the parameter.
         "isOptional": True or False, # Optional. Whether the parameter is optional. Defaults to false.
         "label": "A String", # Required. The label to display for the parameter.