NR-84187 Fix ClassCircularityError when agent attaches

[sdaubin]

Overview

I have an app that crashes when using nri-lsi-java to attach the java agent. Here's how to reproduce this: https://source.datanerd.us/saxon/java-agent-crash

Here's the exception:

at java.base/java.text.FieldPosition.getFieldDelegate(FieldPosition.java:215)at java.base/java.text.DecimalFormat.format(DecimalFormat.java:714)at java.base/java.text.DecimalFormat.format(DecimalFormat.java:507)at ```

We can avoid the error by loading `FieldPosition$Delegate` before we modify class loaders.

### Related Github Issue
[Include a link to the related GitHub issue, if applicable](https://issues.newrelic.com/browse/NR-84187)

### Testing
You can verify the fix with https://source.datanerd.us/saxon/java-agent-crash

### Checks

[ ] Are your contributions backwards compatible with relevant frameworks and APIs?
[ ] Does your code contain any breaking changes? Please describe. 
[ ] Does your code introduce any new dependencies? Please describe.