env migration handles multiline variables with single quotes

[yorickdowne]

What I did

Changed the awk code to handle multi-line single-quote entries, like

STATIC_PEERS='[
  "enode:something",
  "enode:thatthing"
]
'

This pattern is not in use with Eth Docker, but valid. This is adapted from Linea Docker, where the pattern is in use

Main concern: Touching awk code is tricky. I didn't write it to begin with, AI did. And I didn't write this adjustment, AI did.

[yorickdowne]

I tested this on an .env with:

• Empty var
• Single-line no quotes
• Single-line single-quote
• Single-line double-quote
• Multi-line single-quote
• Multi-line double-quote
• Comments

And everything came over fine, with just the ENV_VERSION being changed