Describe the bug

There is a difference in the headers for Content-Type when calling /api/search between version 2.5.0 and v2.6.0

grafana/otel-lgtm:0.7.2 uses tempo 2.5.0

HTTP/1.1 200 OK
Content-Length: 698
Content-Security-Policy: sandbox
Content-Type: application/json
Date: Thu, 19 Sep 2024 00:18:27 GMT
Vary: Accept-Encoding
Via: 1.1 grafana
X-Content-Type-Options: nosniff
X-Frame-Options: deny
X-Xss-Protection: 1; mode=block

grafana/otel-lgtm:0.7.3 uses tempo v2.6.0

HTTP/1.1 200 OK
Content-Length: 752
Content-Security-Policy: sandbox
Content-Type: 
Date: Thu, 19 Sep 2024 00:20:30 GMT
Vary: Accept-Encoding
Via: 1.1 grafana
X-Content-Type-Options: nosniff
X-Frame-Options: deny
X-Xss-Protection: 1; mode=block

The issue still happens in version grafana/otel-lgtm:0.7.4

To Reproduce
Steps to reproduce the behavior:

1. Start Tempo 2.5.0
2. Write a trace
3. Read trace

Expected behavior
Response should include header Content-Type: application/json

Environment:
grafana/otel-lgtm

Additional Context
I'm using RestAssured to perform jsonpath operations but due to the lack of the header tests started failing when docker image version was updated.