Tune up goreleaser and released artifacts

[haoming29]

@aowen-uwmad mentioned a couple of items to improve for various packagings, and this issue is to keep track of the action items ref:

• Standalone binary

mkdir ~/pelican
cd ~/pelican
wget https://github.com/PelicanPlatform/pelican/releases/download/v7.7.3/pelican_Linux_x86_64.tar.gz
tar -xzf pelican_Linux_x86_64.tar.gz

Typically I've seen that the tar step results in a new directory.
Before extraction

$ tree
.
└── pelican_Linux_x86_64.tar.gz

After extraction

$ tree
.
├── LICENSE
├── pelican
├── pelican_Linux_x86_64.tar.gz
└── README.md

What I expected to see

$ tree
.
├── pelican-7.7.3
│   ├── LICENSE
│   ├── pelican
│   └── README.md
└── pelican_Linux_x86_64.tar.gz

(If this is the behavior you want, that is fine, just wanted you to know that this may subvert expectations)

• Debian system install

wget https://github.com/PelicanPlatform/pelican/releases/download/v7.7.4/pelican_7.7.4-1_amd64.deb
sudo dpkg -i pelican_7.7.4-1_amd64.deb
which pelican 
→ /usr/bin/pelican not /bin/pelican

I would have expected this process to have created a default /etc/pelican/pelican.yaml config file. At the very least, I would have expected it to create a /etc/pelican folder.

[matyasselmeci]

1. Tarball contents in a subdirectory: Sure, this will be part of my PR. Note that it is a small compatibility break (for which I will have to adjust some of the OSPool pilot scripts) so a) we need to highlight it in the release notes and b) in the unlikely event that we need to make a 7.8.5 before 7.9.0, we need to make sure this change doesn't get backported.

2. Pelican in /usr/bin instead of /bin: this is normal for RPM systems and there doesn't appear to be a way to change it for Debian without also changing it for RPM, so I'd rather not do this one. Both /bin and /usr/bin should be in PATH for Debian, no?

3. /etc/pelican/pelican.yaml in the pelican rpm/deb: I don't actually know what should be put into a rootly /etc/pelican/pelican.yaml so I'll just make the directory for now.

[brianaydemir]

I don't actually know what should be put into a rootly /etc/pelican/pelican.yaml

As I recall, some packages, or at least apache/httpd, install configuration files that contain nothing but comments documenting the structure of the files and the default values of various options.

See also: #1380.

[jhiemstrawisc]

Is there more work here? I'd like to move this issue to the parking-lot milestone if we don't have an active plan to make related changes for 7.13 or 7.14.

[matyasselmeci]

The first part is done, I don't think the second task should be done, and the third task is essentially #1380; I think we should close this ticket.