[OPIK-2303] [BE] Fix 431 Request Header Fields Too Large errors by increasing Dropwizard header size limit (#3116)

* [NA] Fix 431 Request Header Fields Too Large errors

- Add maxRequestHeaderSize configuration to Dropwizard server config
- Set default to 16KB (16KB) to match ALB/Nginx request line limit
- Add environment variable SERVER_MAX_REQUEST_HEADER_SIZE for configuration
- Update both main config.yml and test config-test.yml
- Add comprehensive E2E test for header size validation
- Test requests below, at, and above the configured limit

* [OPIK-2303] Fix 431 Request Header Fields Too Large errors

- Add maxRequestHeaderSize configuration to Dropwizard server config
- Set default to 16KB (16KB) to match ALB/Nginx request line limit
- Add environment variable SERVER_MAX_REQUEST_HEADER_SIZE for configuration
- Update both main config.yml and test config-test.yml

* Update apps/opik-backend/config.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update apps/opik-backend/src/test/resources/config-test.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update apps/opik-backend/src/test/resources/config-test.yml

fix tests

* Update apps/opik-backend/src/test/resources/config-test.yml

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: Nimrod007

apps/opik-backend/config.yml

@@ -157,6 +157,12 @@ server:
     # Description: If true, all requests with gzip in the Accept-Encoding header will have their response entities
     # compressed and requests with gzip in the Content-Encoding header will have their request entities decompressed.
     enabled: true
+  # HTTP connector configuration for handling large request headers
+  # Default: 16KB (16000 bytes) - matches ALB/Nginx request line limit
+  # Description: Maximum size of request headers to prevent 431 errors from long URLs with many filters
+  applicationConnectors:
+    - type: http
+      maxRequestHeaderSize: ${SERVER_MAX_REQUEST_HEADER_SIZE:-16KB}
 
 # Configuration for batch operations
 batchOperations:

apps/opik-backend/src/test/resources/config-test.yml

@@ -142,6 +142,12 @@ server:
     # Description: If true, all requests with gzip in the Accept-Encoding header will have their response entities
     # compressed and requests with gzip in the Content-Encoding header will have their request entities decompressed.
     enabled: true
+  # HTTP connector configuration for handling large request headers
+  # Default: 16KB (16000 bytes) - matches ALB/Nginx request line limit
+  # Description: Maximum size of request headers to prevent 431 errors from long URLs with many filters
+  applicationConnectors:
+    - type: http
+      maxRequestHeaderSize: 16KB
 
 # Configuration for batch operations
 batchOperations: