Do not display attestation-manifest and use short sha256 instead of full sha256 (#32851)

Related: #24973

Before:

![image](https://github.com/user-attachments/assets/bca17900-5075-4d15-af7a-c71bf8979c04)

After:

![image](https://github.com/user-attachments/assets/c5a24e3b-763b-4463-80db-d4dbd89f7dc4)

Index:
```json
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.index.v1+json",
  "manifests": [
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "digest": "sha256:5967afffdfde104ca1459286a72346baaef8b70ac153325d7a6cd85c7734ac6e",
      "size": 672,
      "platform": {
        "architecture": "amd64",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "digest": "sha256:f9abfcc55320f9ff1f38eeb7dbb4bea10b29c7febfa49ccd7aab9fa02403b9f0",
      "size": 672,
      "platform": {
        "architecture": "arm64",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "digest": "sha256:d70ad19d00c19e40691045cbddc3e8a5a4454c31cc454d1132b13bcaf35b6d46",
      "size": 566,
      "annotations": {
        "vnd.docker.reference.digest": "sha256:5967afffdfde104ca1459286a72346baaef8b70ac153325d7a6cd85c7734ac6e",
        "vnd.docker.reference.type": "attestation-manifest"
      },
      "platform": {
        "architecture": "unknown",
        "os": "unknown"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "digest": "sha256:73bc233bf4eac96a404ce3e0430b698831a4ea7050c878d5f76d1d1f133751dd",
      "size": 566,
      "annotations": {
        "vnd.docker.reference.digest": "sha256:f9abfcc55320f9ff1f38eeb7dbb4bea10b29c7febfa49ccd7aab9fa02403b9f0",
        "vnd.docker.reference.type": "attestation-manifest"
      },
      "platform": {
        "architecture": "unknown",
        "os": "unknown"
      }
    }
  ]
}
```

---------

Co-authored-by: silverwind <[email protected]>

Author: hiifong

Diff for: modules/templates/util_string.go

@@ -60,3 +60,7 @@ func (su *StringUtils) EllipsisString(s string, maxLength int) string {
 func (su *StringUtils) ToUpper(s string) string {
 	return strings.ToUpper(s)
 }
+
+func (su *StringUtils) TrimPrefix(s, prefix string) string {
+	return strings.TrimPrefix(s, prefix)
+}

Diff for: templates/package/content/container.tmpl

@@ -36,11 +36,13 @@
 				</thead>
 				<tbody>
 					{{range .PackageDescriptor.Metadata.Manifests}}
-					<tr>
-						<td><a href="{{$.PackageDescriptor.PackageWebLink}}/{{PathEscape .Digest}}">{{.Digest}}</a></td>
-						<td>{{.Platform}}</td>
-						<td>{{FileSize .Size}}</td>
-					</tr>
+						{{if ne .Platform "unknown/unknown"}}
+						<tr>
+							<td><a href="{{$.PackageDescriptor.PackageWebLink}}/{{PathEscape .Digest}}">{{StringUtils.TrimPrefix .Digest "sha256:" | ShortSha}}</a></td>
+							<td>{{.Platform}}</td>
+							<td>{{FileSize .Size}}</td>
+						</tr>
+						{{end}}
 					{{end}}
 				</tbody>
 			</table>