feat(metrics-exporter): support IPv6 Pod IPs

[michaelbeaumont]

Description

Related to https://github.com/openebs/mayastor/issues/1731. The metrics exporter can't connect to the gRPC client if it's an IPv6 address because there's raw string manipulation that fails in the case of IPv6, no surrounding [] are added.

Motivation and Context

It allows the metrics exporter to connect to IPv6 Pod IPs.

Regression

No

How Has This Been Tested?

Hasn't yet.

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have added unit tests to cover my changes.