Stack already exists - cannot deploy with 2.49.x

[rcoundon]

When deploying a stack with an overridden name, SST tries to create the stack rather than updating it. This is specific to 2.49.x and this fails with a stack already exists error.

See report here: https://discord.com/channels/983865673656705025/1392573271114907729/1392573271114907729