Install yarn via apt in update guides

doc/update/8.17-to-9.0.md

@@ -65,7 +65,10 @@ Since 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
 JavaScript dependencies.
 
 ```bash
-curl --location https://yarnpkg.com/install.sh | bash -
+curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install yarn
 ```
 
 More information can be found on the [yarn website](https://yarnpkg.com/en/docs/install).

doc/update/9.0-to-9.1.md

@@ -65,7 +65,10 @@ Since 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
 JavaScript dependencies.
 
 ```bash
-curl --location https://yarnpkg.com/install.sh | bash -
+curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install yarn
 ```
 
 More information can be found on the [yarn website](https://yarnpkg.com/en/docs/install).

doc/update/9.1-to-9.2.md

@@ -65,7 +65,10 @@ Since 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
 JavaScript dependencies.
 
 ```bash
-curl --location https://yarnpkg.com/install.sh | bash -
+curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install yarn
 ```
 
 More information can be found on the [yarn website](https://yarnpkg.com/en/docs/install).

doc/update/9.2-to-9.3.md

@@ -65,7 +65,10 @@ Since 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
 JavaScript dependencies.
 
 ```bash
-curl --location https://yarnpkg.com/install.sh | bash -
+curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install yarn
 ```
 
 More information can be found on the [yarn website](https://yarnpkg.com/en/docs/install).

doc/update/9.3-to-9.4.md

@@ -65,7 +65,10 @@ Since 8.17, GitLab requires the use of yarn `>= v0.17.0` to manage
 JavaScript dependencies.
 
 ```bash
-curl --location https://yarnpkg.com/install.sh | bash -
+curl --silent --show-error https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install yarn
 ```
 
 More information can be found on the [yarn website](https://yarnpkg.com/en/docs/install).