fix: persist older api keys and prevent missing values

[jcabrero]

This is a modification to the migrations of nilcc-api that prevents losing the old api keys of users when doing the migrations. It also fixes other potential migrations issues that could arise such as empty values or 0 balannce.

[github-actions]

Coverage Report for nilcc-api

Status	Category	Percentage	Covered / Total
🔵	Lines	80.98%	5065 / 6254
🔵	Statements	80.98%	5065 / 6254
🔵	Functions	83.72%	252 / 301
🔵	Branches	84.66%	508 / 600

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
nilcc-api/migrations/1774000000000-UsdBasedPricing.ts	56%	100%	50%	56%	58-96
nilcc-api/src/data-source.ts	85.88%	85%	72.72%	85.88%	111-112, 124-125, 168-169, 176-186, 189-194

Generated in workflow #200 for commit 78b2807 by the Vitest Coverage Report Action