Fix azuread_privileged_access_group_eligibility_schedule resource update functionality

[h0597]

My goal with this pull request is to improve the azuread_privileged_access_group_eligibility_schedule resource.

Updating the 'Update' functionality to use the adminUpdate instead of adminAssign As per Microsoft graph documentation

adminUpdate: For administrators to change existing eligible assignments. instead of adminAssign: For administrators to assign group membership or ownership eligibility to principals.

I found this issue in relation to this problem: #1412

As this is my first fork pull request, I hope this way is correct to do it. If not, please let me know so I can improve the pull request.

[SPALLADI]

Any luck with merging the PR?

[relent0r]

I'm interested in this one too as I've hit the issue where you get 400 errors and are unable to apply after any changes are required. I need to manually delete all the assignments and reapply to make it work which given how slow the azure interface is for this is really painful.

[farflungfish]

This is definitely the solution we are looking for; total pain in the rear without it at the moment having to recreate role assignments.

[xzuttz]

An issue for us as well. Looking forward to a solution soon.

[srjennings]

PR is ready for review, folks are looking for review/merge status
CC @katbyte @jackofallops

[kevinfalconer-seccl]

Issue that we are facing at the moment as well, hopefully will be looked at soon!

[xgryph]

bump!

[andymaxseccl]

This seems like a simple fix, can anyone check out this PR please? @hashicorp-cloud

[aaron-warner-nzta]

I've been doing testing on this fix today. It looks like it causes a problem where the state is not being updated after the change is applied.

I think its because when the update takes place a new assignment is created on the MS side but the state is not updated with this new assignment information and still has the original ID reference. So every time it reads from the API it uses the previous assignments ID which contains the original configuration so Terraform see's no changes being required.