Fix grpc security variables name and missing exec qualifier in docker.dev

[jmelinav]

What this PR does / why we need it:
Grpc security variable names in application.yml are incorrect. Also exec qualifiers are missing from DockerFile.dev
Which issue(s) this PR fixes:

Related #823

Does this PR introduce a user-facing change?:No

previous behavior : enabling grpc security and setting valid server.crt and server.key, throws an error. 
Also docker images build using DockerFile.dev will not boot.

With this PR, enabling security shouldn't throw any error if valid server.crt and server.key are set.
Images build using DockerFile.dev will boot without any errors.

[feast-ci-bot]

Hi @jmelinav. Thanks for your PR.

I'm waiting for a feast-dev member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[jmelinav]

/kind bug

[jmelinav]

/assign @pyalex

[feast-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jmelinav, woop

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[woop]

/lgtm

[woop]

Remember to add a release note to bugs, thanks for the contribution @jmelinav!

[jmelinav]

/test test-end-to-end-auth