[filesystem] Fix misleading OBS comment in hadoop-uber shade config

[thswlsqls]

Purpose

• The shade-plugin comment in paimon-filesystems/paimon-hadoop-uber/pom.xml read Relocate all OBS related classes, but this module is the Hadoop uber jar: it relocates the Hadoop stack (guava, asm, netty, curator, httpcomponents, htrace, jackson), not OBS. The wording was copy-pasted from paimon-obs-impl; corrected to "Hadoop".
• Sibling convention: paimon-oss-impl/pom.xml:165 says "OSS", paimon-obs-impl/pom.xml:84 says "OBS".
• Relocations and artifactSet are unchanged, so the produced jar is identical.

Tests

• Wording-only fix, no behavior change — no test added.
• Jar output is unchanged; the full shade build is covered by fork CI. A standalone local apache-rat:check only flags pre-existing bundled LICENSE* files, unrelated to this change.