Incorrect Repository URL for OracleLinux 7 Server

### Please provide a brief summary of the bug

Following the instructions from https://adoptium.net/installation/linux/ does not work for OracleLinux 7 because yum/dnf variable "releasever" differs from the https://packages.adoptium.net/ path.

### Please provide steps to reproduce where possible

The following instructions from https://adoptium.net/installation/linux/ were performed:

```
# Uncomment and change the distribution name if you are not using CentOS/RHEL/Fedora
DISTRIBUTION_NAME=oraclelinux

cat < /etc/yum.repos.d/adoptium.repo
[Adoptium]
name=Adoptium
baseurl=https://packages.adoptium.net/artifactory/rpm/${DISTRIBUTION_NAME:-$(. /etc/os-release; echo $ID)}/\$releasever/\$basearch
enabled=1
gpgcheck=1
gpgkey=https://packages.adoptium.net/artifactory/api/gpg/key/public
EOF

yum install temurin-8-jdk
```

### Expected Results

Package temurin-8-jdk should be installed via yum.

### Actual Results

yum exits with error:

```
# yum install temurin-8-jdk
Loaded plugins: ulninfo
https://packages.adoptium.net/artifactory/rpm/oraclelinux/7Server/x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
Trying other mirror.

One of the configured repositories failed (Adoptium),
and yum doesn't have enough cached data to continue. At this point the only
safe thing yum can do is fail. There are a few ways to work "fix" this:
[...]

failure: repodata/repomd.xml from Adoptium: [Errno 256] No more mirrors to try.
https://packages.adoptium.net/artifactory/rpm/oraclelinux/7Server/x86_64/repodata/repomd.xml: [Errno 14] HTTPS Error 404 - Not Found
```

### What Java Version are you using?

None

### What is your operating system and platform?

OracleLinux 7 Server x86_64

### How did you install Java?

rpm package through Adoptium repository + yum

### Did it work before?

_No response_

### Did you test with other Java versions?

_No response_

### Relevant log output

_No response_

Start with the Linux installation instructions at https://adoptium.net/installation/linux/ and reproduce the documented yum setup on OracleLinux 7 Server x86_64. Verify that the generated Adoptium repository URL resolves its repodata and that yum can install temurin-8-jdk; done means the documented instructions work without the 404 for releasever=7Server.

Written by the indexing model from the issue text.