fix: remove hardcoded bearer

[marco-ippolito]

Followup of #1240

Description:
This change makes the mirror usable.
Right now Immagine we setup the value of mirror-token to foo.
In this line the value is used as

setup-node/src/distributions/base-distribution.ts

Line 106 in 2951748

headers['Authorization'] = `Bearer ${this.nodeInfo.mirrorToken}`;

Bearer foo but in other places such as:

setup-node/src/distributions/base-distribution.ts

Line 149 in 2951748

this.nodeInfo.mirrorToken

setup-node/src/distributions/base-distribution.ts

Line 210 in 2951748

this.nodeInfo.mirrorToken

its used as is.

But if we change the value to Bearer foo,

setup-node/src/distributions/base-distribution.ts

Line 106 in 2951748

headers['Authorization'] = `Bearer ${this.nodeInfo.mirrorToken}`;

here it becomes Bearer Bearer foo which is incorrect, but works everywhere else.

So this PR makes it that if its a Bearer, the user needs to be explicit.

Related issue:
Add link to the related issue.

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.