fix(docker): increase jetty request header size

[Athemis]

What this PR does / why we need it:

This PR sets an environment variable for the Solr docker container, increasing jetty response header size from the default value of 8192 to 102400 as recommended in the installation guide. This prevents errors when importing larger metadata blocks.

Which issue(s) this PR closes:

• Closes #12047

Special notes for your reviewer:

Suggestions on how to test this:

1. Deploy Dataverse using docker using compose files from current develop branch or 6.8
2. Import a large metadata block
3. Observe error as described in #12047
4. Recreate containers with the environment variable set/this PR applied
5. No error should be thrown.

Does this PR introduce a user interface change? If mockups are available, please link/include them here:

no

Is there a release notes update needed for this change?:

Additional documentation: