[DASHTree] Limit insert live segs to uncovered interval cases

[CastagnaIT]

Description

Due to last cleanups to manifest updates now the update behaviour its a bit changed
and if sync is a bit late (could be due to unsupported UTCTiming) currently could insert new live segments
where this should not happens when the period interval is full covered by segments

Motivation and context

fix #1350

How has this been tested?

to test insert live segments: https://livesim.dashif.org/livesim/sts_1691768189/sid_ac07c88f/ato_10/testpic_2s/Manifest.mpd
to test the other case i have no sample stream, feedback is reported by users in issue

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• I have read the Contributing document
• My code follows the Code Guidelines of this project
• My change requires a change to the Wiki documentation
• I have updated the documentation accordingly

[glennguy]

Sorry - I approved without checking that a review was requested. Please ping again when ready