Describe the bug
az keyvault secret list has an optional argument that specifies the maximum number of results to return. When a user specifies this argument, they receive an error Parameter 'maxresults' failed to meet validation requirement.

To Reproduce
$ az keyvault secret list --vault-name my-keyvault --maxresults 1000
Parameter 'maxresults' failed to meet validation requirement.

Expected behavior
I would expect the secrets to be listed.

Environment summary
$ cat os-release | grep VERSION=
VERSION="18.04.2 LTS (Bionic Beaver)"
$ az --version | grep azure-cli
azure-cli 2.0.61
$ bash --version | grep 'GNU bash'
GNU bash, version 4.4.19(1)-release (x86_64-pc-linux-gnu)
$ python3 --version
Python 3.6.7

Additional context
Related to #7311