deck file convert does not work well with environment variables for 3.10 -> 3.14 conversion

[harshadixit12]

deck file convert expects the environment variables to be present, and resolves them while converting.
https://kongstrong.slack.com/archives/C04349E4KRC/p1775115564350019

[mheap]

https://github.com/Kong/go-database-reconciler/pull/444/changes
#1977