[Fleet] removed extraneous '/downloads' in path for curl commands (el…

…astic#204660)

## Summary

Removed the extra `/downloads` portion of the curl command, as it is
already returned in the base url.
Closes elastic#204462 

Before: 

![image](https://github.com/user-attachments/assets/5a156aca-ea2b-4703-97b3-f7a5e4ae6ab1)

After: 

![image](https://github.com/user-attachments/assets/d5c9f0d4-1452-40c1-b8df-4473584ac288)

x-pack/plugins/fleet/public/components/enrollment_instructions/standalone/index.tsx

@@ -22,24 +22,24 @@ export const StandaloneInstructions = ({
   const { windows: windowsDownloadSourceProxyArgs, curl: curlDownloadSourceProxyArgs } =
     getDownloadSourceProxyArgs(downloadSourceProxy);
 
-  const linuxDebCommand = `curl -L -O ${downloadBaseUrl}/downloads/beats/elastic-agent/elastic-agent-${agentVersion}-amd64.deb ${curlDownloadSourceProxyArgs}
+  const linuxDebCommand = `curl -L -O ${downloadBaseUrl}/beats/elastic-agent/elastic-agent-${agentVersion}-amd64.deb ${curlDownloadSourceProxyArgs}
 sudo dpkg -i elastic-agent-${agentVersion}-amd64.deb \nsudo systemctl enable elastic-agent \nsudo systemctl start elastic-agent`;
 
-  const linuxRpmCommand = `curl -L -O ${downloadBaseUrl}/downloads/beats/elastic-agent/elastic-agent-${agentVersion}-x86_64.rpm ${curlDownloadSourceProxyArgs}
+  const linuxRpmCommand = `curl -L -O ${downloadBaseUrl}/beats/elastic-agent/elastic-agent-${agentVersion}-x86_64.rpm ${curlDownloadSourceProxyArgs}
 sudo rpm -vi elastic-agent-${agentVersion}-x86_64.rpm \nsudo systemctl enable elastic-agent \nsudo systemctl start elastic-agent`;
 
-  const linuxCommand = `curl -L -O ${downloadBaseUrl}/downloads/beats/elastic-agent/elastic-agent-${agentVersion}-linux-x86_64.tar.gz ${curlDownloadSourceProxyArgs}
+  const linuxCommand = `curl -L -O ${downloadBaseUrl}/beats/elastic-agent/elastic-agent-${agentVersion}-linux-x86_64.tar.gz ${curlDownloadSourceProxyArgs}
 tar xzvf elastic-agent-${agentVersion}-linux-x86_64.tar.gz
 cd elastic-agent-${agentVersion}-linux-x86_64
 sudo ./elastic-agent install`;
 
-  const macCommand = `curl -L -O ${downloadBaseUrl}/downloads/beats/elastic-agent/elastic-agent-${agentVersion}-darwin-aarch64.tar.gz ${curlDownloadSourceProxyArgs}
+  const macCommand = `curl -L -O ${downloadBaseUrl}/beats/elastic-agent/elastic-agent-${agentVersion}-darwin-aarch64.tar.gz ${curlDownloadSourceProxyArgs}
 tar xzvf elastic-agent-${agentVersion}-darwin-aarch64.tar.gz
 cd elastic-agent-${agentVersion}-darwin-aarch64
 sudo ./elastic-agent install`;
 
   const windowsCommand = `$ProgressPreference = 'SilentlyContinue'
-Invoke-WebRequest -Uri ${downloadBaseUrl}/downloads/beats/elastic-agent/elastic-agent-${agentVersion}-windows-x86_64.zip -OutFile elastic-agent-${agentVersion}-windows-x86_64.zip ${windowsDownloadSourceProxyArgs}
+Invoke-WebRequest -Uri ${downloadBaseUrl}/beats/elastic-agent/elastic-agent-${agentVersion}-windows-x86_64.zip -OutFile elastic-agent-${agentVersion}-windows-x86_64.zip ${windowsDownloadSourceProxyArgs}
 Expand-Archive .\elastic-agent-${agentVersion}-windows-x86_64.zip -DestinationPath .
 cd elastic-agent-${agentVersion}-windows-x86_64
 .\\elastic-agent.exe install`;