Remove temp index on project_statistics

What does this MR do and why?

This MR:

• Closes #382358 (closed)
• Removes tmp_index_project_statistics_uploads_size

Migrations:

UP:

main: == 20221221110733 RemoveTempIndexForProjectStatisticsUploadSizeMigration: migrating 
main: -- transaction_open?()
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.0006s
main: -- indexes(:project_statistics)
main:    -> 0.0026s
main: -- remove_index(:project_statistics, {:algorithm=>:concurrently, :name=>"tmp_index_project_statistics_uploads_size"})
main:    -> 0.0015s
main: == 20221221110733 RemoveTempIndexForProjectStatisticsUploadSizeMigration: migrated (0.0083s) 

Down:

main: == 20221221110733 RemoveTempIndexForProjectStatisticsUploadSizeMigration: reverting 
main: -- transaction_open?()
main:    -> 0.0000s
main: -- view_exists?(:postgres_partitions)
main:    -> 0.1530s
main: -- index_exists?(:project_statistics, [:project_id], {:name=>"tmp_index_project_statistics_uploads_size", :where=>"uploads_size <> 0", :algorithm=>:concurrently})
main:    -> 0.0053s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0003s
main: -- add_index(:project_statistics, [:project_id], {:name=>"tmp_index_project_statistics_uploads_size", :where=>"uploads_size <> 0", :algorithm=>:concurrently})
main:    -> 0.0031s
main: -- execute("RESET statement_timeout")
main:    -> 0.0007s
main: == 20221221110733 RemoveTempIndexForProjectStatisticsUploadSizeMigration: reverted (0.1741s)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.