RFR: 8432: Better exception handling for Email Trigger failure

[Aymane Harmaz]

This PR : 
- Restructures the exception message displayed when the email send trigger fails, to show the root cause of the issue at the top before the trigger message
- Increases the initial height of alert dialog for a better visibility

Alert dialog after the change : 

<img width="609" height="348" alt="Screenshot 2025-12-08 at 12 23 02" src="https://github.com/user-attachments/assets/0f933b11-4b46-44e3-89fa-377633ff7f8c" />

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Commit messages:
 - 8432: Better exception handling for Email Trigger failure

Changes: https://git.openjdk.org/jmc/pull/692/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=692&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8432
  Stats: 19 lines in 3 files changed: 13 ins; 3 del; 3 mod
  Patch: https://git.openjdk.org/jmc/pull/692.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/692/head:pull/692

PR: https://git.openjdk.org/jmc/pull/692