Shorten release time: create staging repository earlier in workflow?

[rtyley]

It takes over a minute to create a staging repository - should we be doing it earlier, even if we don't start the upload till the artifact is signed?

2024-09-13 11:43:33.709Z  info [SonatypeService] sbt-sonatype version: 3.10.0  - (SonatypeService.scala:27)
20[24](https://github.com/guardian/pan-domain-authentication/actions/runs/10848437411/job/30105684943#step:5:25)-09-13 11:43:33.712Z  info [SonatypeService] sonatypeRepository  : https://oss.sonatype.org/service/local  - (SonatypeService.scala:28)
2024-09-13 11:43:33.712Z  info [SonatypeService] sonatypeProfileName : com.gu  - (SonatypeService.scala:29)
[info] Preparing a new staging repository for [sbt-sonatype] pan-domain-authentication 6.0.0-PREVIEW.support-accepting-multiple-public-keys.2024-09-13T1139.8e972972
2024-09-13 11:43:33.713Z  info [SonatypeClient] Reading staging repository profiles...  - (SonatypeClient.scala:105)
2024-09-13 11:43:33.794Z  info [SonatypeClient] Reading staging profiles...  - (SonatypeClient.scala:119)
2024-09-13 11:43:45.896Z  info [SonatypeService] No previous staging repository for [sbt-sonatype] pan-domain-authentication 6.0.0-PREVIEW.support-accepting-multiple-public-keys.2024-09-13T1139.8e972972 was found  - (SonatypeService.scala:101)
2024-09-13 11:43:45.939Z  info [SonatypeClient] Creating a staging repository in profile com.gu with a description key: [sbt-sonatype] pan-domain-authentication 6.0.0-PREVIEW.support-accepting-multiple-public-keys.2024-09-13T1139.8e972972  - (SonatypeClient.scala:1[25](https://github.com/guardian/pan-domain-authentication/actions/runs/10848437411/job/30105684943#step:5:26))
2024-09-13 11:45:04.882Z  info [SonatypeClient] Created successfully: comgu-4810  - (SonatypeClient.scala:138)
2024-09-13 11:45:05.180Z  info [SonatypeClient] Uploading bundle /tmp/artifact_staging to https://oss.sonatype.org/service/local/staging/deployByRepositoryId/comgu-4810/  - (SonatypeClient.scala:299)