W-10067032 fix: default hep value

[soridalac]

What does this PR do?

make the default value to be static value only in the help text

What issues does this PR fix or reference?

@W-10067032@

[WillieRuemmele]

QA Notes

---

✅ : in --help

 ➜  ../../oss/plugin-deploy-retrieve/bin/run.js project convert source  --help
Convert source-formatted files into metadata that you can deploy using Metadata API.

USAGE
  $ sf project convert source [--json] [--flags-dir <value>] [--api-version <value>] [-r <value>] [-d <value>] [-n
    <value>] [-p <value>... | -x <value> | -m <value>...]

FLAGS
  -d, --output-dir=<value>     [default: metadataPackage_>timestamp<] Output directory to store the Metadata
                               API–formatted files in.

✅ : and in action

 ➜  ../../oss/plugin-deploy-retrieve/bin/run.js project convert source  --source-dir force-app 
Source was successfully converted to Metadata API format and written to the location: /Users/william.ruemmele/projects/scratches/ebikes-lwc/metadataPackage_1725658574209