fix(helm): parse error when using extraEnvs

[zbindenren]

This should fix the following error when using envVars:

Error: YAML parse error on kubenurse/templates/daemonset.yaml: error converting YAML to JSON: yaml: line 42: mapping values are not allowed in this context

Use --debug flag to render out invalid YAML

[coveralls]

Pull Request Test Coverage Report for Build 3312883279

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 7 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-1.3%) to 79.284%

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Files with Coverage Reduction	New Missed Lines	%
internal/kubediscovery/nodewatcher.go	7	81.63%
<!--	Total:	7		-->

Totals
Change from base Build 2714940868:	-1.3%
Covered Lines:	421
Relevant Lines:	531

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💛 - Coveralls

[djboris9]

lgtm @zbindenren