fix(PDNS): removal of custom resolver location resource.

[arjunchauhanibm]

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Relates OR Closes #0000

Output from acceptance testing:

$ make testacc TESTARGS='-run=TestAccXXX'

...

[arjunchauhanibm]

Custom resolver location resource was already deprecated. We are now completing the 3rd step of removing the resource which is mentioned in - https://github.ibm.com/NetworkTribe/PrivateDNS-CP/issues/7838

[arjunchauhanibm]

These 2 PRs were used to deprecate the resource earlier.

#3820
#4296