Avoid putting URLs into 'code' field in diagnostics

[anthony-c-martin]

Closes #14570

Before:

After (clicking the code takes you to the right link):

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Test this change out locally with the following install scripts (Action run 9993985923)

VSCode

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-vsix.sh) --run-id 9993985923

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-vsix.ps1) } -RunId 9993985923"

Azure CLI

• Mac/Linux

  bash <(curl -Ls https://aka.ms/bicep/nightly-cli.sh) --run-id 9993985923

• Windows

  iex "& { $(irm https://aka.ms/bicep/nightly-cli.ps1) } -RunId 9993985923"

[github-actions]

Dotnet Test Results

    72 files   -     36      72 suites   - 36   23m 16s ⏱️ - 7m 56s
10 955 tests  -     20  10 955 ✅  -     20  0 💤 ±0  0 ❌ ±0 
25 806 runs   - 12 899  25 806 ✅  - 12 899  0 💤 ±0  0 ❌ ±0 

Results for commit b61d8d5. ± Comparison against base commit 684e6d4.

♻️ This comment has been updated with latest results.