update excluded_interface_re type to String"

[florusboth]

What does this PR do?

fix the excluded_interface_re type to string as per documentation in https://github.com/DataDog/integrations-core/blob/master/network/datadog_checks/network/data/conf.yaml.default

Motivation

Current version expected an array of strings which broke the network/conf.yaml file as datadog-agent threw an error

    network (2.1.2)
    ---------------
      Instance ID: network:9358677f0d90eae3 [ERROR]
      Configuration Source: file:/etc/datadog-agent/conf.d/network.d/conf.yaml
      Total Runs: 11
      Metric Samples: Last Run: 0, Total: 0
      Events: Last Run: 0, Total: 0
      Service Checks: Last Run: 0, Total: 0
      Average Execution Time : 1ms
      Last Execution Date : 2021-05-07 11:02:30 UTC (1620385350000)
      Last Successful Execution Date : Never
      Error: unhashable type: 'list'
      Traceback (most recent call last):
        File "/opt/datadog-agent/embedded/lib/python3.8/site-packages/datadog_checks/base/checks/base.py", line 897, in run
          self.check(instance)
        File "/opt/datadog-agent/embedded/lib/python3.8/site-packages/datadog_checks/network/network.py", line 105, in check
          self._exclude_iface_re = re.compile(exclude_re)
        File "/opt/datadog-agent/embedded/lib/python3.8/re.py", line 252, in compile
          return _compile(pattern, flags)
        File "/opt/datadog-agent/embedded/lib/python3.8/re.py", line 294, in _compile
          return _cache[type(pattern), pattern, flags]
      TypeError: unhashable type: 'list'

Additional Notes

Describe your test plan

[albertvaka]

👋 Hi! Thanks for finding this bug and opening a PR 😃

There are couple more places that need to be updated for this fix to work, though:

• The example in the same file:

  puppet-datadog-agent/manifests/integrations/network.pp

  Lines 17 to 19 in 417ea0a

  	# excluded_interface_re => [
  	# 'eth1.*'
  	# ]

• The template yaml file where this variable is used:

  puppet-datadog-agent/templates/agent-conf.d/network.yaml.erb

  Lines 13 to 17 in 417ea0a

  	<% if !@excluded_interface_re.empty? -%>
  	excluded_interface_re:
  	<%- (@excluded_interface_re.each do |interface| -%>
  	- <%= interface %>
  	<% end ) -%>

Could you give those a look? 🙇

[florusboth]

of course, thanks for reviewing. I updated the PR with the 2 fixes.
/florus

[albertvaka]

Thanks for the quick turnaround 🎉 And thanks again for the fix! Merging ✅