chore: add confirmation to migrate_grant

[thelostone-mc]

Description

• adds in confirmation before migrating grants over
• remove the old_scripts

[codecov]

Codecov Report

Merging #6508 into master will increase coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #6508      +/-   ##
==========================================
+ Coverage   27.06%   27.09%   +0.02%     
==========================================
  Files         291      291              
  Lines       26685    26685              
  Branches     3949     3949              
==========================================
+ Hits         7223     7229       +6     
+ Misses      19195    19189       -6     
  Partials      267      267              

Impacted Files	Coverage Δ
app/grants/management/commands/migrate_grant.py	0.00% <0.00%> (ø)
app/retail/emails.py	22.34% <0.00%> (ø)
app/dashboard/sync/etc.py	14.63% <0.00%> (ø)
app/dashboard/views.py	11.24% <0.00%> (+0.01%)	⬆️
app/dashboard/embed.py	31.60% <0.00%> (+3.44%)	⬆️

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