fix(vmware): Explicitly set IPv6 to dhcp when there is no IPv6 addr given

[PengpengSun]

Proposed Commit Message

fix(vmware): Explicitly set IPv6 to dhcp when there is no IPv6 addr given

When there is no IPv6 addr given in the customization configuration,
we shall set IPv6 type to dhcp6, then customized Linux network will be
set to dhcp IPv6 explicitly.

Additional Context

Test Steps

Merge type

• [x] Squash merge using "Proposed Commit Message"
• [x] Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[PengpengSun]

Thanks for this contribution @PengpengSun! Would you mind modifying the first line of your commit message in the PR description to be:

fix(vmware): Explicitly set IPv6 to dhcp when there is no IPv6 addr given

Thanks!

Thanks @a-dubs , I've updated it.