[RemoteRuntime] Fix adding http trigger mode for sync

[royischoss]

📝 Description

Fix https://iguazio.atlassian.net/browse/ML-12025 adding http trigger mode to trigger spec when using sync mode

---

🛠️ Changes Made

Added mode field for default http trigger of serving function + adding to with_http method the mode when sync mode is chosen, by default or explicit

---

✅ Checklist

• I updated the documentation (if applicable)
• I have tested the changes in this PR
• I confirmed whether my changes are covered by system tests
  • If yes, I ran all relevant system tests and ensured they passed before submitting this PR
  • I updated existing system tests and/or added new ones if needed to cover my changes
• If I introduced a deprecation:
  • I followed the Deprecation Guidelines
  • I updated the relevant Jira ticket for documentation

---

🧪 Testing

added unit test to check the trigger spec, checked that serving behave as expected for both modes

---

🔗 References

• Ticket link: Ticket
• Design docs links:
• External links:

---

🚨 Breaking Changes?

• Yes (explain below)
• No

---

🔍️ Additional Notes

[gtopper]

Minor comments – LGTM otherwise!