fix: sanity check startPosition

[jcosentino11]

Issue #, if available:

Description of changes:

Why is this change necessary:

How was this change tested:

Any additional information or context required to review the change:

Checklist:

• Updated the README if applicable
• Updated or added new unit tests
• Updated or added new integration tests
• Updated or added new end-to-end tests

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[github-actions]

Unit Tests Coverage Report

File	Coverage	Lines	Branches
All files	77%	84%	71%	✅
com.aws.greengrass.logmanager.services.DiskSpaceManagementService	71%	83%	60%	✅
com.aws.greengrass.logmanager.CloudWatchLogsUploader	90%	97%	83%	✅
com.aws.greengrass.logmanager.LogManagerService	68%	81%	55%	✅
com.aws.greengrass.logmanager.LogManagerService$CurrentProcessingFileInformation	79%	89%	68%	✅
com.aws.greengrass.logmanager.PositionTrackingBufferedReader	86%	87%	86%	✅
com.aws.greengrass.logmanager.CloudWatchAttemptLogsProcessor	88%	89%	86%	✅
com.aws.greengrass.logmanager.util.ConfigUtil	85%	85%	85%	✅
com.aws.greengrass.logmanager.util.CloudWatchClientFactory	53%	53%	0%	❌
com.aws.greengrass.logmanager.model.CloudWatchAttemptLogInformation	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.EventType	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.ComponentType	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.ProcessingFiles	68%	80%	56%	✅
com.aws.greengrass.logmanager.model.LogFile	85%	78%	92%	✅
com.aws.greengrass.logmanager.model.LogFileGroup	70%	75%	64%	✅

Minimum allowed coverage is 65%

Generated by 🐒 cobertura-action against d7fcaee

[github-actions]

Integration Tests Coverage Report

File	Coverage	Lines	Branches
All files	67%	76%	59%	✅
com.aws.greengrass.logmanager.services.DiskSpaceManagementService	47%	55%	40%	❌
com.aws.greengrass.logmanager.CloudWatchLogsUploader	42%	42%	41%	❌
com.aws.greengrass.logmanager.LogManagerService	81%	93%	70%	✅
com.aws.greengrass.logmanager.LogManagerService$CurrentProcessingFileInformation	46%	55%	37%	❌
com.aws.greengrass.logmanager.PositionTrackingBufferedReader	72%	82%	63%	✅
com.aws.greengrass.logmanager.CloudWatchAttemptLogsProcessor	67%	73%	61%	✅
com.aws.greengrass.logmanager.util.ConfigUtil	48%	61%	35%	❌
com.aws.greengrass.logmanager.util.CloudWatchClientFactory	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.CloudWatchAttemptLogInformation	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.EventType	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.ComponentType	100%	100%	0%	✅
com.aws.greengrass.logmanager.model.ProcessingFiles	76%	85%	68%	✅
com.aws.greengrass.logmanager.model.LogFile	45%	49%	42%	❌
com.aws.greengrass.logmanager.model.LogFileGroup	65%	74%	57%	✅

Minimum allowed coverage is 58%

Generated by 🐒 cobertura-action against d7fcaee