fix: Improve error message when networking peering reaches a failed status

[AgustinBettati]

Description

Link to any related issue(s): CLOUDP-268949

Reproduced a FAILED status by creating 2 network_peering resources with same azure account and cidr block range (using separate projects).

Before

mongodbatlas_network_peering.other: Still creating... [40s elapsed]
╷
│ Error: error creating MongoDB Network Peering Connection: unexpected state 'FAILED', wanted target 'AVAILABLE, PENDING_ACCEPTANCE'. last error: %!s(<nil>)
│ 
│   with mongodbatlas_network_peering.other,
│   on main.tf line 53, in resource "mongodbatlas_network_peering" "other":
│   53: resource "mongodbatlas_network_peering" "other" {
│ 

After

mongodbatlas_network_peering.other: Still creating... [40s elapsed]
╷
│ Error: Peer networking is in a failed state: Could not create peering connection in Atlas Azure account because a peer with an overlapping CIDR block already exists.
│ 
│   with mongodbatlas_network_peering.other,
│   on main.tf line 53, in resource "mongodbatlas_network_peering" "other":
│   53: resource "mongodbatlas_network_peering" "other" {
│ 

Type of change:

• Bug fix (non-breaking change which fixes an issue). Please, add the "bug" label to the PR.
• New feature (non-breaking change which adds functionality). Please, add the "enhancement" label to the PR. A migration guide must be created or updated if the new feature will go in a major version.
• Breaking change (fix or feature that would cause existing functionality to not work as expected). Please, add the "breaking change" label to the PR. A migration guide must be created or updated.
• This change requires a documentation update
• Documentation fix/enhancement

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• I have signed the MongoDB CLA
• I have read the contributing guides
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• I have added tests that prove my fix is effective or that my feature works per HashiCorp requirements
• I have added any necessary documentation (if appropriate)
• I have run make fmt and formatted my code
• If changes include deprecations or removals I have added appropriate changelog entries.
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Further comments

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