[FINE] Corrects sections and their names in New Subnet form

[petrblaho]

solves https://bugzilla.redhat.com/show_bug.cgi?id=1535369

Steps for Testing/QA

1. Add OpenStack provider
2. Networks > Subnets
3. Configuration > Add a new Cloud Subnet

Results without patch:
Form on page has wrong form section captions. Original BZ can describe little different parts b/c #3254 got merged in the meantime.

Results with patch (expected):
Form on page has "Network Provider", "Placement" and "Cloud Subnet details" sections.

Backport of #3148

[miq-bot]

Checked commit https://github.com/petrblaho/manageiq-ui-classic/commit/21f3bd3758e23fd2e0765f5271a49a85890f4382 with ruby 2.3.3, rubocop 0.52.0, haml-lint 0.20.0, and yamllint 1.10.0
0 files checked, 0 offenses detected
Everything looks fine. 🍰

[dclarizio]

@petrblaho can you please add screenshots? Thanks, Dan

[petrblaho]

@dclarizio sure!

Before Network Manager is chosen:

After Network Manager is chosen:

[dclarizio]

@petrblaho I just noticed this PR is for Fine only, is there a corresponding fix for Gaprindashvili or is this not an issue there? We normally fix bugs upstream, then back port them.

[petrblaho]

@dclarizio Gaprindashvili and master is working correctly.

I have seen some bigger refactoring in this file's history in Gaprindashvili and master and it was dependant on some other feature with I believe is not in Fine.

So this patch is Fine only b/c some changes were not backported to Fine in the past.

[petrblaho]

The latest common commit in history of that view template is e98fc97 from Jan 2017.

Then there was a lot of changes with section changes in 51d030c#diff-338ecb79799bff25e172f8849a48dbbd which did not went into Fine branch.

There is #3148 which was backported to Gaprindashvili but not to Fine. Maybe backport it to Fine too instead of this one?

[simaishi]

Backport of #3148 will conflict, so I think we can take this. I will mark this as a backport of that PR.

@dclarizio are you good with this change?

[dclarizio]

Backport of #3148 will conflict, so I think we can take this. I will mark this as a backport of that PR.

@dclarizio are you good with this change?

I think that is a question for @petrblaho . . . @petrblaho, can you confirm this should be merged as a backport of #3148?

[petrblaho]

@dclarizio @simaishi yes, in the end both BZs describe and both PRs solve the same issue - wrong sections and nesting of elements in template around the same two sections (differences are here b/c of other newer changes not present in Fine)

[dclarizio]

@simaishi good to go