Transaction Tags Object Array Search Does Not Work During Alert Creation

### Environment

SaaS (https://sentry.io/)

### Steps to Reproduce

- Navigate to Alerts -> Create a Throughput Metric Alert for Transactions

- Add in Step 2 "Filter Events" tags[customer_id] is APPLES

Was able to replicate this behavior in multiple browsers in the new and old UI.

### Expected Result

I would expect that while entering tags[] I would be able to search and have provided the available tags and value IE APPLES. Instead this has to be manually input and shows as a raw search.

Once Alert has been saved however if you choose to edit this alert you are then able to search the tags/values successfully which shows that Search does work for this filter.

I would also expect this to work given the docs: https://docs.sentry.io/concepts/search/#explicit-tag-syntax

### Actual Result

See above

Related to and examples found in internal ticket [#154997](https://sentry.zendesk.com/agent/tickets/154997)

### Product Area

Alerts

### Link

_No response_

### DSN

_No response_

### Version

_No response_

Start at Alerts → Create a Throughput Metric Alert, Step 2 (“Filter Events”), and compare its tag search with the edit-alert flow described in the report. Done means tags[customer_id] exposes searchable tags and values such as APPLES during creation instead of requiring raw input; verify the documented explicit-tag syntax remains supported.

Written by the indexing model from the issue text.