fix(sqllab): ignore schema validate while loading

[justinpark]

SUMMARY

This commit fixes the side effect of #22695.

The initial selected schema option has gone because the schema validator checks the existence with the empty schemaOptions before loaded.
This commit skips the validation before loaded.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Before:

before--skip-schema-check.mov

After:

after--skip-schema-check.mov

TESTING INSTRUCTIONS

disable "SQLLAB_BACKEND_PERSISTENCE"
select a schema and open a new tab
check the schema preassigned from the above the schema selection

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[justinpark]

It makes another regression. let me close this and revert #22695