ci(java): remove leaked COPILOT_SDK_DEFAULT_CONNECTION from step env

The java-sdk-inprocess CI job set COPILOT_SDK_DEFAULT_CONNECTION=inprocess
as a step-level environment variable, which leaked into surefire unit tests.
The Maven inprocess profile already configures this env var only in
failsafe's <environmentVariables>, per the design: 'Leave Surefire on its
standard transport; only Failsafe ITs use InProcess.' Removing the
redundant step-level env var fixes all 195 surefire test errors.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: c4e523e3-9d39-4598-90ec-54d959c44ce8

Author: edburns

.github/workflows/java-sdk-tests.yml

@@ -44,7 +44,6 @@ jobs:
       - name: Run Java SDK tests (InProcess)
         env:
           CI: "true"
-          COPILOT_SDK_DEFAULT_CONNECTION: inprocess
         run: mvn clean verify -Pinprocess
 
       - name: Generate Test Report Summary