Pelican client has wrong user-agent header when requesting object

[haoming29]

Pelican Version:
Run ./pelican --version to get version number.

Pelican Service:

• Client

Describe the bug
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Pelican client should attach the project name to user-agent header we requesting objects in the federation. However, currently the user-agent is grab

To Reproduce
Steps to reproduce the behavior.

• Spin up federation in a box
• Put a file under origin exported directory
• Request the file using pelican object get
• Go to Prometheus metric at /api/v1.0/prometheus/query?query=xrootd_transfer_bytes and watch for the label proj. The entry with path == your origin exported namespace should have corresponding proj="grab"

Expected behavior
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Screenshots
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Desktop (please complete the following information):

• OS: [e.g. Linux, MacOS]
• Browser: [e.g. chrome, safari, if the bug relates to any web user interface]

Additional context
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