[BUG] Function schema tool names exceed 64 character limit causing ValidationException

## Bug Description
When importing Bedrock Agents with function-based action groups, tool names exceed 64-character limit, causing ValidationException during agent invocation.

## Steps to Reproduce
1. Create Bedrock Agent with function schema action group (long names)
2. Run: `agentcore import-agent --agent-id AGENT_ID --target-platform strands`
3. Invoke the deployed agent
4. Error occurs: "Member must have length less than or equal to 64"

## Expected Behavior
Tool names should be automatically truncated to stay within 64-character limit

## Actual Behavior
Tool names like `vacationsactiongroup___vacationsactiongroup_get_available_vacations_days` (67 chars) exceed limit

## Root Cause
In `base_bedrock_translate.py` line 1317, function schema uses default prune length (50) but doesn't account for the `{clean_action_group_name}___` prefix added later.

## Suggested Fix
Apply same length calculation as OpenAPI schema:

```
tool_name = prune_tool_name(
f"{action_group_name}_{clean_func_name}",
length=(54 - len(clean_action_group_name))
)
```

## Environment
- OS: macOS
- Python: 3.12
- Agent type: Function schema action groups

Start in base_bedrock_translate.py around line 1317 and compare the function-schema naming logic with the OpenAPI schema handling. Reproduce with `agentcore import-agent --agent-id AGENT_ID --target-platform strands`, then invoke the deployed agent. Done means generated function tool names stay within 64 characters and the ValidationException no longer occurs.

Written by the indexing model from the issue text.