fix(api): Add additional check to allow update endpoint requests without deployment type specified

[deadlycoconuts]

What this PR does / why we need it:
As a follow up to #455 and #466, this tiny change to the update endpoint endpoint allows requests that do not specify a deployment type to avoid the check that checks for different deployment types between a deployed endpoint and the new endpoint configuration. What will instead happen if a deployment type isn't specified is that the existing deployed endpoint's deployment type will be used.

The main change is just the addition of another boolean condition, but there's a unit test that I added which is just an almost exact copy of another unit test case.

Which issue(s) this PR fixes:
Fixes #

Does this PR introduce a user-facing change?:

NONE

Checklist

• Added unit test, integration, and/or e2e tests
• Tested locally
• Updated documentation
• Update Swagger spec if the PR introduce API changes
• Regenerated Golang and Python client if the PR introduce API changes

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[ariefrahmansyah]

LGTM! Thanks Zi Yi for quick fix!