[HUDI-7859] Rename instant files to be consistent with 0.x naming format when downgrade

[watermelon12138]

Change Logs

When downgrading the hudi table version from 8 to 7, rename the instant file to match the 0.x naming format.

Impact

EightToSevenDowngradeHandler

Risk level (write none, low medium or high below)

low

Documentation Update

Describe any necessary documentation update if there is any new feature, config, or user-facing change. If not, put "none".

• The config description must be updated if new configs are added or the default value of the configs are changed
• Any new feature or user-facing change requires updating the Hudi website. Please create a Jira ticket, attach the ticket number here and follow the instruction to make changes to the website.

Contributor's checklist

• [ ] Read through contributor's guide
• [ ] Change Logs and Impact were stated clearly
• [ ] Adequate tests were added if applicable
• [ ] CI passed