DXCDT-450: Remove deprecated tenant pages

[willvedd]

🔧 Changes

Management of the error, guardian MFA and change password page templates via the auth0_tenant resource has been deprecated in favor of the auth0_pages resource. This PR removes the code associated with this deprecation.

📚 References

• Auth0 Pages Resource PR

🔬 Testing

N/A.

📝 Checklist

• All new/changed/fixed functionality is covered by tests (or N/A)
• I have added documentation for all new/changed functionality (or N/A)

[codecov-commenter]

Codecov Report

Merging #711 (fe76288) into v1 (408384e) will decrease coverage by 0.11%.
The diff coverage is 83.09%.

Additional details and impacted files

@@            Coverage Diff             @@
##               v1     #711      +/-   ##
==========================================
- Coverage   87.60%   87.50%   -0.11%     
==========================================
  Files          85       85              
  Lines       13484    13392      -92     
==========================================
- Hits        11813    11718      -95     
- Misses       1264     1266       +2     
- Partials      407      408       +1     

Impacted Files	Coverage Δ
internal/auth0/tenant/expand.go	100.00% <ø> (ø)
internal/auth0/tenant/flatten.go	88.23% <ø> (+7.22%)	⬆️
internal/auth0/tenant/resource.go	97.09% <ø> (-0.60%)	⬇️
internal/auth0/page/flatten.go	74.28% <67.85%> (-25.72%)	⬇️
internal/auth0/page/expand.go	90.47% <92.50%> (+2.01%)	⬆️
internal/auth0/page/resource.go	82.72% <100.00%> (ø)